This cinnamon sugar snack cake is soft, buttery, and lightly spiced, with a crisp cinnamon-sugar topping baked right on top. An easy, one-pan cake made with basic ingredients and perfect for everyday baking.
Preheat the oven to 350°F (175°C). Grease a 9-inch square baking pan or line it with parchment.
In a medium bowl, whisk together the flour, baking powder, cinnamon, and salt.
In a large mixing bowl, beat the butter, brown sugar, and granulated sugar with an electric mixer on medium speed until light and fluffy. Add the eggs one at a time, mixing well after each. Mix in the vanilla.
Add the dry ingredients in three portions, alternating with two portions of the buttermilk. Mix just until combined.
To make the topping and bake:
Stir together the topping sugars and cinnamon in a small bowl.
Spread the batter evenly in the prepared pan, gently brush with melted butter, and sprinkle the cinnamon-sugar mixture evenly on top.
Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Cool in the pan on a wire rack before slicing.
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Notes
Buttermilk substitute: If you don’t have buttermilk, you can make a quick substitute by combining ¾ cup milk with 2 teaspoons white vinegar or lemon juice. Let it sit for 5 minutes before using.
Topping tip: The cinnamon-sugar topping may look generous before baking, but it melts and settles into a perfectly balanced, lightly crisp layer.
Slicing:For the cleanest slices, let the cake cool completely before cutting.
Storage: Store the cake tightly covered at room temperature for up to 3 days. For longer storage, refrigerate for up to 5 days or freeze for up to 2 months.