Almond Sheet Cake with Fluffy Almond Frosting

Almond sheet cake is a tender, buttery cake flavored with almond extract and topped with a soft almond frosting. Baked in a 9-by-13-inch pan, it’s easy to slice for a gathering and needs no layers or special decorating tools.

Ingredients

2 cups (250 g) all-purpose flour, spooned into the measuring cup and leveled
1½ cups (300 g) granulated sugar
1 teaspoon baking powder
½ teaspoon baking soda
½ teaspoon fine salt
¾ cup (170 g) unsalted butter, cut into pieces
1 cup (240 ml) water
½ cup (120 ml) sour cream, at room temperature
2 large eggs, at room temperature
1 teaspoon vanilla extract
1 teaspoon almond extract
½ cup (113 g) unsalted butter, softened, for the frosting
3 cups (360 g) powdered sugar, sifted if lumpy
3 tablespoons (45 ml) milk, plus more as needed
½ teaspoon almond extract, for the frosting
¼ cup (20 g) sliced almonds, lightly toasted, for garnish (optional)

Instructions

Heat the oven to 350°F (175°C). Grease a 9-by-13-inch (23-by-33-cm) metal baking pan, then line the bottom with parchment paper if you want easier removal. Let the eggs and sour cream come to room temperature while you prepare the batter.
Whisk the flour, sugar, baking powder, baking soda, and salt in a large heatproof bowl. In a saucepan, bring the ¾ cup (180 ml) water and ¾ cup (170 g) butter to a boil over medium heat, stirring until the butter melts. Pour the hot mixture into the dry ingredients and whisk until no dry pockets remain. The mixture will look thin; that is expected.
In a separate bowl, whisk the sour cream, eggs, vanilla, and 1 teaspoon almond extract until smooth. Add this mixture to the flour mixture and whisk just until combined. Scrape the bowl once, but do not beat the batter for a long time, which can make the cake dense.
Pour the batter into the prepared pan and spread it evenly into the corners. Bake for 28–32 minutes, rotating the pan once if your oven browns unevenly. The cake is ready when the center springs back lightly and a toothpick inserted in the middle comes out clean or with a few moist crumbs. If checking with a thermometer, the center should reach about 200–210°F (93–99°C); avoid touching the pan with the probe.
Set the pan on a rack and cool the cake completely, about 30–40 minutes. Do not frost it while warm: the butter in the frosting will melt and slide. For quicker cooling, leave the cake in the pan and set the pan on a wire rack with space around it.
To make the frosting, beat the softened ½ cup (113 g) butter in a bowl until creamy. Add the powdered sugar in two or three additions, mixing on low so it does not scatter. Beat in the milk and ½ teaspoon almond extract, then beat briefly until smooth and spreadable. Add another teaspoon of milk at a time if it is too stiff, or a little powdered sugar if it is too loose.
Spread the frosting over the cooled cake, reaching the edges. Sprinkle with toasted sliced almonds, if using. Cut into 12 pieces with a clean knife; wipe the blade between cuts for neater slices.

Tips

Measure flour by weight when possible. If using cups, fluff the flour, spoon it into the cup, and level it rather than scooping directly from the bag; too much flour can dry out the crumb.
Use room-temperature eggs and sour cream so they mix evenly into the warm butter mixture. If they are cold, place the eggs in warm water for 5–10 minutes and let the sour cream sit out briefly.
Almond extract varies in strength, so measure it carefully. Do not replace it with an equal amount of almond emulsion without checking its label; some products are more concentrated.
For a softer frosting, add milk gradually. If the cake is being served somewhere warm, keep it chilled until shortly before serving because the buttercream softens at room temperature.

Serving Suggestions

Serve slices at cool room temperature, when the cake and frosting are soft and aromatic. Fresh berries such as raspberries or strawberries provide a bright contrast, while coffee, black tea, or a glass of milk makes a simple accompaniment. For a celebration, add the toasted almonds just before serving so they stay crisp.

Variations

Berry-topped: Serve each frosted slice with fresh berries, or scatter a small handful over the cake shortly before serving. Avoid adding juicy fruit far in advance, since it can make the frosting wet.
Citrus almond: Add 1 teaspoon finely grated lemon or orange zest to the batter. Citrus brings a fresh note without changing the cake’s basic texture.
Toasted-almond batter: Replace ¼ cup (30 g) of the all-purpose flour with finely ground blanched almonds. The crumb will be slightly richer and more delicate; do not use coarse almond meal as a direct replacement.
Reduced frosting: Halve the frosting ingredients for a thinner layer. For a simple glaze instead, whisk 1½ cups (180 g) powdered sugar with 2–3 tablespoons (30–45 ml) milk and ¼ teaspoon almond extract, then drizzle over the fully cooled cake.

Storage and Reheating

Because the frosting contains butter and milk, refrigerate the cake within 2 hours of serving. Cover the pan tightly or transfer slices to an airtight container; they keep well in the refrigerator for up to 4 days. Let a slice stand at room temperature for about 20–30 minutes before eating for a softer texture. Reheating is usually unnecessary; if you prefer a warm slice, warm it without frosting for about 8–10 seconds in a microwave, then add frosting after warming.

To freeze, chill the frosted cake until the frosting is firm, then wrap individual portions tightly and place them in a freezer-safe container for up to 2 months. Thaw overnight in the refrigerator, then bring to room temperature before serving. Freezing may slightly soften the frosting, but the cake remains sliceable.

Frequently Asked Questions

Can I make almond sheet cake without sour cream?
Yes. Use the same amount of plain, full-fat Greek yogurt. It provides similar moisture and tang; avoid thin, pourable yogurt because it can loosen the batter.

Can I bake this in a glass pan?
Yes, but glass heats differently from metal and may take a few extra minutes. Keep the oven at 350°F (175°C), begin checking at 28 minutes, and rely on the center’s doneness rather than the clock alone. Grease the pan well and do not place a cold glass pan into a preheated oven.

How do I know when the cake is done?
The center should spring back lightly, and a toothpick inserted in the middle should come out clean or with a few moist crumbs. If the top is browning before the center is done, loosely cover it with foil for the remaining bake time.

Can I make the cake ahead?
Yes. Bake it a day ahead, cool it completely, cover it, and refrigerate it unfrosted. Make the frosting and finish the cake on the day you plan to serve it, or frost it the night before and keep it covered in the refrigerator.

Can I use salted butter?
Yes. Use the same quantity of salted butter and reduce the added salt in the batter to ¼ teaspoon. Salt levels vary by brand, so the result may taste slightly different.

Can I bake this as cupcakes?
Yes. Divide the batter among lined muffin cups, filling each about two-thirds full. Bake at 350°F (175°C) for roughly 16–20 minutes, checking that the centers spring back and a toothpick comes out clean. The yield depends on your pan and how full you fill each cup.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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