Homemade Cake Recipe with Buttercream Frosting

brown butter coffee cake (half size) *this is for half a 9x9 pan. so feel free to increase by 1.5 the recipe for a larger cake or tall loaf! baking times will vary :) browned butter: 3/4 cup unsalted butter -> brown it *brown the butter and cool. this is going to be used throughout the recipe. cinnamon sugar swirl: 2 tbsp (25g) sugar 1 tsp ground cinnamon streusel: 6 tbsp (45 g) ap flour 6 tbsp (75 g) brown sugar 1 1/2 tsp cinnamon 4 tbsp (55 g) browned butter, cooled slightly coffee cake: 6 tbs