Why this recipe works:
- Moistened rolled oats add texture and nutty flavor.
- Whisking all of the ingredients results in an open, tender, crumb.
- Under the broiler, the buttery brown sugar and coconut topping melts and sets right on top of the cake.
Read more: One Bowl Baking: Coconut Oatmeal Cake
- Yield:make one 9-inch square pan
- Active time: 15 minutes
- Total time:1 hour
- For Cake:
- 1 cup rolled oats
- 3/4 cup boiling water
- 1/2 cup milk
- 1/2 plus 1/8 teaspoon salt
- 8 tablespoons (4 ounces) unsalted butter, very soft
- 1 3/4 cup (12 1/4 ounces) packed light brown sugar
- 2 teaspoons vanilla extract
- 2 large eggs
- 1/2 cup shredded sweetened coconut
- 1 1/4 cups (6 1/4 ounces) all purpose flour
- 1 teaspoon baking soda
- 1 teaspoon cinnamon
- For Topping:
- 6 tablespoons (3 ounces) unsalted butter, very soft
- 3/4 cup (5 1/4 ounces) packed light brown sugar
- 3 tablespoons milk
- 2 cups shredded sweetened coconut
- 1 cup walnuts (or pecans), chopped
Combine oats, boiling water, and milk; let sit 20 minutes. Adjust oven rack to upper and lower middle position and preheat to 350°F. Grease 9- by 9-inch pan.
Add salt, butter, sugar, and vanilla to oat mixture and stir to combine. Stir in eggs and coconut. Add flour, baking soda, and cinnamon to bowl, then stir until completely combined. Pour into prepared pan and bake on middle rack until just set, about 30 minutes.
While cake is baking, mix topping in same unwashed bowl: toss butter, brown sugar, milk, coconut, and nuts to form moist crumbs.
As soon as cake is baked, remove from oven and spread topping over the top. Return pan to oven and increase heat to broil. Briefly heat until topping melts and coconut is lightly toasted, about 1 minute. Transfer pan to wire rack to cool.