An oatmeal cookie in a cup is a single-serving, soft-centered cookie made with oats, flour, brown sugar, and a little butter, then cooked in the microwave. It comes together in minutes with no oven or baking sheet, making it a handy dessert when you want one warm cookie without a full batch.
Ingredients
- 1 tablespoon (14 g) unsalted butter
- 1 tablespoon (13 g) packed light brown sugar
- 1 teaspoon (4 g) granulated sugar
- ⅛ teaspoon vanilla extract
- 1 tablespoon (15 ml) milk
- 3 tablespoons (24 g) all-purpose flour
- ¼ teaspoon ground cinnamon
- ⅛ teaspoon baking powder
- A small pinch of fine salt, about 1/16 teaspoon
- 3 tablespoons (24 g) old-fashioned rolled oats
- 1 tablespoon (10 g) raisins or chocolate chips (optional)
Instructions
- Choose a microwave-safe mug or small bowl that holds at least 10 ounces (300 ml). Add the butter and microwave for 15 to 20 seconds, just until melted. If the butter is very hot, let it cool for about 30 seconds so it does not make the mixture greasy.
- Stir the brown sugar and granulated sugar into the melted butter until smooth. Mix in the vanilla and milk.
- Add the flour, cinnamon, baking powder, and salt. Stir just until no dry flour remains; scraping the bottom and sides helps prevent dry pockets. Fold in the oats and, if using, raisins or chocolate chips. The dough should be thick and slightly sticky, not pourable.
- Press the dough into an even layer in the mug, leaving room at the top for it to rise. Microwave on high for 45 seconds, then check the center. Continue in 10-second bursts as needed, usually for 10 to 20 seconds more. Microwave power varies, so the total cook time is a guide rather than a guarantee.
- Let the mug stand for 1 minute before eating. The cookie will continue to set as it rests; it should look moist but not have wet, raw-looking batter in the center. Eat it warm from the mug, taking care because the mug may be hot.
Tips
- Measure flour lightly. Spoon flour into the tablespoon measure and level it off rather than packing it in. Too much flour makes a small microwave cookie dry and crumbly.
- Use a roomy mug. A 10-ounce (300 ml) or larger microwave-safe mug gives the dough space to rise. Avoid metal mugs, and do not use a mug with metallic decoration.
- Cook gradually. Start with 45 seconds and add short bursts only if needed. Overcooking is the most common cause of a tough, dry result; the center firms up during the standing time.
- Choose your oats thoughtfully. Old-fashioned rolled oats give the cookie a chewy texture. Quick oats work in the same quantity but make it softer; steel-cut oats stay too firm and are not suitable here.
Serving Suggestions
Serve the cookie warm, straight from the mug, with a spoon. A small scoop of vanilla ice cream, a spoonful of plain or vanilla yogurt, or a drizzle of warm caramel makes it more dessert-like. For a simpler finish, add a few extra chocolate chips or a pinch of cinnamon on top while the cookie is still warm.
If sharing, divide the dough between two small microwave-safe cups before cooking and check each one early, since smaller portions can cook faster. This recipe is designed as a single serving, so sharing it from one mug gives smaller portions.
Variations
- Raisin-cinnamon: Use raisins instead of chocolate chips and increase the cinnamon to ⅜ teaspoon. A pinch of nutmeg can add a warm, spiced note.
- Chocolate chip: Use chocolate chips and omit the raisins. A teaspoon of chopped walnuts or pecans adds crunch; keep the total add-ins to about 1 tablespoon so the dough holds together.
- Nut butter: Replace 1 teaspoon of the melted butter with 1 teaspoon of peanut or almond butter. The cookie will have a denser texture and a noticeable nutty flavor.
- Dairy-free: Use a plant-based butter stick and unsweetened oat or soy milk in equal amounts. A tub-style spread may contain more water, which can make the cookie softer.
- Gluten-free: Substitute a cup-for-cup gluten-free flour blend that includes a binder, and use oats labeled gluten-free if needed. Texture can vary by blend, so check the center before adding extra microwave time.
Storage and Reheating
This cookie is best eaten soon after cooking, while warm and soft. If you have leftovers, transfer them from the mug to a covered container and refrigerate within 2 hours. Refrigerate for up to 3 days; the cookie will become firmer as it cools. Freezing a single mug cookie is possible but often makes its texture less pleasant after thawing.
To reheat, place the cookie in a microwave-safe dish and heat for 8 to 12 seconds, then add a few seconds if needed. Let it sit briefly before eating, and avoid repeated long heating, which quickly dries it out. If refrigerated, reheat only the portion you plan to eat.
Frequently Asked Questions
Can I make an oatmeal cookie in a cup without an egg?
Yes. This recipe contains no egg, which suits a small microwave portion because an egg can make the center rubbery. The milk and melted butter provide enough moisture to bring the dough together.
Why is my mug cookie dry or tough?
It may have been overcooked, or too much flour may have been packed into the spoon measures. Microwave ovens vary considerably, so use short bursts and allow the cookie to rest for 1 minute before deciding whether it needs more cooking.
Can I use quick oats instead of rolled oats?
Yes. Use 3 tablespoons (24 g) of quick oats. They absorb moisture more readily and create a softer, less distinct oat texture. Do not use steel-cut oats, which will remain hard in this short cooking time.
Can I double the recipe in one mug?
It is better not to double it in a standard mug. A larger amount heats unevenly and may overflow; the outside can become tough before the center cooks. Make two separate portions in roomy mugs instead, and microwave them one at a time for more predictable results.
Can I make the dough ahead?
For the best texture, mix and cook it right before serving. You can measure the dry ingredients ahead and keep them covered at room temperature, then add the butter, sugar, vanilla, and milk when ready to cook. Do not leave prepared dough at room temperature for an extended period.
Is the center supposed to look soft?
Yes, it should be tender and moist, but not show wet, raw batter. Microwave cooking can be uneven, so check the center and use another 10-second burst if it is still visibly undercooked. Resting for 1 minute helps the cookie finish setting.
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