Grandma’s Oatmeal Raisin Cookie Bars

Grandma’s oatmeal raisin cookie bars are soft, chewy squares made with oats, plump raisins, brown sugar, and cinnamon. Baked in one pan and sliced after cooling, they bring the familiar flavor of oatmeal cookies with less shaping and fuss; family versions vary, but this one keeps the method simple and dependable.

Ingredients

1 cup (226 g) unsalted butter, softened
1 cup packed (213 g) light brown sugar
½ cup (100 g) granulated sugar
2 large eggs, at room temperature
2 teaspoons (10 ml) vanilla extract
1½ cups (190 g) all-purpose flour, spooned into the measuring cup and leveled
1 teaspoon baking soda
1 teaspoon ground cinnamon
½ teaspoon fine salt
3 cups (270 g) old-fashioned rolled oats
1 cup (150 g) raisins
1 tablespoon (15 ml) milk, only if needed to loosen the dough

Instructions

Heat the oven to 350°F (175°C). Line a 9-by-13-inch (23-by-33-cm) metal baking pan with parchment, leaving a little overhang on the long sides so you can lift out the cooled bars. Lightly grease the parchment if it is not nonstick.
In a large bowl, beat the softened butter with the brown and granulated sugars until creamy and evenly blended, about 2 minutes with a hand mixer. Scrape down the bowl. Add the eggs one at a time, beating briefly after each, then mix in the vanilla. The mixture may look slightly curdled; that is fine.
In a separate bowl, whisk together the flour, baking soda, cinnamon, and salt. Add the dry ingredients to the butter mixture and mix on low just until no dry flour remains. Stir in the oats and raisins with a sturdy spoon or spatula. The dough should be thick and scoopable. If it seems unusually dry and will not come together, mix in the optional tablespoon of milk.
Transfer the dough to the prepared pan. Press it into an even layer, reaching the corners; damp fingertips or the back of a lightly greased spoon help keep it from sticking. Avoid packing it extremely firmly, which can make the finished bars dense.
Bake for 23–27 minutes, rotating the pan once if your oven browns unevenly. The edges should be set and golden, while the center looks just set and may still feel soft. A wooden pick inserted near the center should come out with a few moist crumbs, not wet batter. Do not wait for the center to look dry; the bars continue to set as they cool.
Set the pan on a wire rack and cool completely, about 30 minutes, before lifting out the slab and cutting it into 16 squares. For cleaner slices, use a sharp knife and wipe it between cuts. The eggs are fully baked in this cookie bar; USDA guidance requiring 160°F (71°C) applies to egg dishes such as soft-cooked or custardy preparations, not as a routine thermometer target for cookies. If the center is visibly raw or batter-like, return the pan to the oven and bake a few minutes longer.

Tips

Measure flour gently. Spoon it into the cup and level it rather than scooping straight from the bag. Too much flour can make the bars dry and crumbly.
Use softened, not melted, butter. Butter should give slightly when pressed but still hold its shape. Melted butter can make the dough greasy and change the texture.
Choose rolled oats for chew. Quick oats work in a pinch but make a softer, less distinct texture. Steel-cut oats are not a suitable direct substitute because they stay too firm.
Let the pan cool before cutting. Slicing while warm can cause the soft center to break apart. If you like warm bars, cut them after they set, then warm individual portions briefly.

Serving Suggestions

Serve the bars at room temperature with coffee, tea, or a glass of milk. For dessert, warm one portion and add a small scoop of vanilla ice cream or a spoonful of plain yogurt. They are sturdy enough for lunchboxes and picnics, but keep them covered and out of direct sun; do not leave perishable accompaniments such as dairy-based toppings unrefrigerated.

Variations

For a little crunch, replace up to ½ cup (75 g) of the raisins with chopped walnuts or pecans. To use chocolate, swap in ½ cup (85 g) chocolate chips for part of the raisins; the bars will taste sweeter and less traditionally spiced. You can also add ½ cup (75 g) chopped dates in place of some raisins, or increase the cinnamon to 1½ teaspoons for a warmer flavor.

For a different dried-fruit option, use the same weight of chopped dried cranberries or golden raisins. If using cranberries, expect a brighter, slightly tart bite. Avoid adding several extra handfuls of mix-ins, since too much can make the slab difficult to hold together.

Storage and Reheating

Cool the bars completely, then store them in an airtight container at room temperature for up to 4 days. Keep layers separated with parchment if stacking. For longer storage, freeze cut bars in a sealed freezer-safe container, with parchment between layers, for up to 3 months; thaw at room temperature. Refrigeration is not necessary for plain cookie bars and may make them firm. Discard them if they have been left in conditions where they may be contaminated or otherwise spoiled; refrigerate perishable foods within 2 hours.

To serve a bar warm, microwave one at a time for about 8–12 seconds, then check and add a few seconds if needed. Heating times vary by microwave, so avoid overheating, which can dry out the oats and make the raisins very hot.

Frequently Asked Questions

Can I use quick oats instead of old-fashioned oats?
Yes. Use the same volume and weight, but expect a more uniform, softer texture with less chew. Do not substitute steel-cut oats without changing the recipe, as they need more liquid and cooking time.

Why are my oatmeal raisin bars dry?
The most common causes are too much flour or overbaking. Spoon and level the flour, begin checking at 23 minutes, and take the pan out when the center is just set rather than waiting for it to become firm and dry.

Can I make the dough ahead?
You can cover the mixed dough and refrigerate it for up to 24 hours. Let it sit at room temperature for about 20–30 minutes so it is easier to press into the pan, then bake as directed; a chilled slab of dough may need a few extra minutes.

Can I make these bars without a mixer?
Yes. Use a sturdy wooden spoon or spatula and thoroughly cream the softened butter and sugars by hand before adding the eggs. It takes more effort, but the mixture does not need to become especially fluffy.

How do I know when the bars are done?
The edges should be golden and set, and the middle should look just set rather than liquid. A few moist crumbs on a pick are a good sign; the bars firm as they cool, so avoid baking until the center is hard.

Can I halve the recipe?
Yes. Bake half the quantities in an 8-inch (20-cm) square pan and start checking at about 20 minutes. The exact time depends on the pan and oven, so use the set edges and just-set center as your guide.

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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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