Preheat the oven to 375F. Spray an 8x8 pan with non-stick cooking spray.
In a medium sized bowl, whisk together the sugar, melted butter, milk, and egg until combined.
1/2 cup sugar, 1/4 cup melted butter or neutral oil (light olive or avocado), 3/4 cup milk, 1 egg
In a large bowl, mix together the flour, baking powder, cinnamon, and salt. Add the wet ingredients to the dry ingredients and mix with a spatula until just combined. Pour into the prepared 8×8 pan. Set aside.
In a medium-sized bowl, mix together the topping ingredients and pour or drop by spoonfuls over the pan of batter. Drop spoonfuls of topping over the batter with the batter still peaking through.
1/4 cup melted butter, 1/4 cup white sugar, 1/4 cup brown sugar, 1 teaspoon cinnamon
Bake for 30 to 35 minutes or until a toothpick inserted comes out clean. Allow to cool for 15 minutes before serving. If desired, serve topped with butter!
Store leftovers in an airtight container at room temp for up to 3 days.
Video
Notes
Prep Tips - The batter will be thicker using a 1:1 gluten free flour blend than all-purpose flour. After adding the cinnamon topping, swirl a butter knife through the cake batter a few times to allow the topping to incorporate into the batter while baking to make the pools of cinnamony sugar goodness. This step is unneeded if using regular flour.Baking Tips -Be careful to not overbake or the cake will be dry. However if this happens, it can be remedied by cutting a piece in half and topping each half with a pat of butter when serving. You can even pop it in the microwave for 10-15 seconds to allow the butter to melt more.