Oatmeal cookie icing is a simple powdered-sugar glaze flavored with vanilla and thinned with milk until it is easy to drizzle or spread. It adds a sweet finish to chewy oatmeal cookies without hiding their cinnamon-and-oat flavor, and it sets into a light coating as it dries.
Ingredients
- 1 cup (120 g) powdered sugar, sifted if lumpy
- 1 tablespoon (15 ml) milk, plus up to 2 teaspoons (10 ml) more as needed
- ½ teaspoon (2.5 ml) vanilla extract
- ⅛ teaspoon fine salt
Instructions
- Make sure the oatmeal cookies are completely cool before icing. Warm cookies can melt the glaze, making it run off rather than set. If the cookies have just come out of the oven, allow at least 30 minutes for cooling; that cooling time is not included in the recipe facts because it depends on the cookies.
- Put the powdered sugar and salt in a small bowl. Add 1 tablespoon (15 ml) milk and the vanilla. Stir slowly with a spoon or small whisk until the mixture is smooth. Scrape the sides and bottom of the bowl so no dry sugar remains.
- Check the consistency. For a drizzle, lift the spoon and let the icing fall back into the bowl; it should form a ribbon that disappears into the surface in about 5 to 10 seconds. For a thicker icing that can be spread with a small knife, use less liquid. If it is too thick, add the extra milk a few drops at a time, stirring after each addition. If it gets too thin, mix in powdered sugar 1 teaspoon (about 3 g) at a time.
- Drizzle the icing over the cooled cookies with a spoon, or spread a thin layer across each cookie. The quantity is enough for a light finish on about 24 average-sized cookies; coverage will vary with cookie size and how much icing you use. Let the cookies sit uncovered for 15 minutes, or until the glaze is no longer tacky, before stacking or storing them.
Tips
- Measure the liquid carefully. Powdered sugar can vary slightly in how tightly it is packed, and a small excess of milk can turn a drizzle into a thin, runny glaze. Begin with the stated amount and adjust gradually.
- Fix the texture in small steps. Add liquid by drops when the icing is too stiff, or add powdered sugar a teaspoon at a time when it is too loose. Stir thoroughly before deciding it needs another adjustment.
- Sift out stubborn lumps. If your sugar is clumpy, sift it before mixing. If lumps remain, press them against the side of the bowl with the back of a spoon; whisking harder may not dissolve them.
- Keep the glaze covered while you work. Powdered-sugar icing dries quickly at the surface. Press a piece of plastic wrap directly against any icing you are not using, then stir it again before applying.
Serving Suggestions
Use the glaze on fully cooled oatmeal cookies, including plain, raisin, chocolate-chip, or spiced versions. A fine zigzag gives cookies a modest sweet finish, while a thin spread makes a more even layer. If you want a decorative look, drizzle in one direction and let the icing set before adding a second crossing drizzle.
Serve the cookies after the icing has dried so the glaze does not stick to fingers or plates. For a cookie platter, place them in a single layer at first; once the icing is firm, they can be arranged in a serving basket or stacked with parchment between layers.
Variations
- Lemon glaze: Replace 1 teaspoon (5 ml) of the milk with lemon juice and add ½ teaspoon (2.5 ml) finely grated lemon zest. The result is tangier and slightly softer, so add the remaining liquid cautiously.
- Maple icing: Replace the vanilla with ½ teaspoon (2.5 ml) maple extract, or replace 1 teaspoon (5 ml) of milk with pure maple syrup. Syrup makes the glaze a little softer and adds a gentle maple flavor.
- Cinnamon glaze: Stir in ¼ teaspoon ground cinnamon. This complements cinnamon-spiced oatmeal cookies; for a smoother appearance, mix the spice thoroughly before adding any extra milk.
- Dairy-free version: Use an unsweetened plant-based milk in the same quantity. Oat or soy milk works well, though the flavor and final sheen may differ slightly from a glaze made with dairy milk.
- Almond flavor: Use ¼ teaspoon (1.25 ml) almond extract in place of the vanilla. Almond extract is potent, so avoid substituting it spoon for spoon.
Storage and Reheating
Let the icing set before storing the cookies. Keep iced oatmeal cookies in an airtight container at room temperature for up to 3 days, or refrigerate them for up to 5 days if the cookie recipe or any topping requires refrigeration. Refrigerate perishable foods within 2 hours; this simple powdered-sugar glaze does not by itself require refrigeration, but the cookies may have other ingredients that do. Separate layers with parchment to protect the finish.
For longer storage, freeze the cookies in a sealed freezer-safe container for up to 2 months, ideally in a single layer until the icing is firm. Thaw at room temperature in the container to reduce condensation on the glaze. Do not reheat iced cookies: warming can soften or melt the icing. If you prefer warm cookies, warm them before icing, then let them cool completely before glazing.
Frequently Asked Questions
Can I make oatmeal cookie icing without milk?
Yes. Use water in the same amount, adding it a few drops at a time. The glaze will still set, although it may taste a little less creamy. Lemon juice can replace some of the liquid for a brighter flavor.
How do I make the icing thicker or thinner?
For thicker icing, stir in powdered sugar 1 teaspoon (about 3 g) at a time. For thinner icing, add milk or water a few drops at a time. Mix completely after each addition, since the consistency can change noticeably with very little liquid.
How long does oatmeal cookie icing take to dry?
A thin drizzle usually becomes dry to the touch in about 15 minutes at room temperature. A thicker coating or a humid room may need 30 minutes or longer. Leave cookies uncovered while the glaze sets.
Can I ice cookies while they are warm?
No. Warm cookies can melt the glaze and make it runny or uneven. Cool them completely on a rack first; if you are short on time, moving the cookies to a rack helps air circulate around them.
Can I make the icing ahead?
Yes. Keep it in a small airtight container with plastic wrap pressed directly onto its surface and refrigerate for up to 3 days. Let it come to room temperature, stir until smooth, and adjust with a few drops of milk or water if it has thickened.
Why is my glaze transparent instead of white?
A thin glaze can look translucent, especially over a dark cookie. Stir in more powdered sugar for an opaque coating, or apply a second thin layer after the first has set. A thicker application will take longer to dry.
Related
- Chewy Oatmeal Cookie Recipe with Soft Centers
- Oatmeal Raisin Cookie Calories and a Lighter Recipe
- Smoking Behind the Supermarket With You: A Manga-Inspired Bento
More recipes to cook
Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
Spotted an error? Tell us and we will correct it (corrections policy).