This coffee cake recipe is easy to make and a favorite for breakfast, brunch or any celebration. It's light and moist with the best cinnamon streusel filling and crumb topping!
Preheat the oven to 350°F. Line an 8x8-inch baking dish with parchment paper, if desired.
Wet ingredients. In a large bowl, whisk together the 1/2 cup oil, 1/2 milk, 1/2 cup sugar, 1 egg, and 1 teaspoon vanilla.
Dry ingredients. Add 1 1/2 cups flour, 2 teaspoons baking powder, and 1/2 teaspoon salt to the bowl and mix together with a wooden spoon. Pour half the batter into the baking dish.
Filling
In a small bowl, combine the 1/4 cup brown sugar and 1 teaspoon cinnamon. Sprinkle over the top of the batter. Drizzle 1 Tablespoon melted butter evenly over the top. Pour the remaining batter over the filling.
Topping
In a small bowl combine 1/4 cup flour, 1/4 cup sugar, and 3 Tablespoons butter. Crumble evenly over the batter.
Cover dish loosely with foil and bake 25 minutes. Remove foil and bake 10 more minutes, or until a toothpick inserted in the center comes out clean.
Remove from the oven and let cool at least 15 minutes before serving. Slice into 9 squares and serve.
Notes
Crumb topping: If you'd prefer more of a crumb mixture on top, feel free to make half a batch of this crumble topping to add to the top. You'll only need half of the topping listed above for the middle. Doubling: You can double the recipe for a crowd. Bake in a 9x13-inch baking dish for an additional 5 to 10 minutes. Storage: Store leftover cake in a covered container for up to 3 days. Freeze up to 3 months.