Prepare the apple cake by creaming together brown butter and sugar
Beat in eggs and vanilla
Mix in dark rum if using
Combine flour, baking powder, and salt in a separate bowl
Fold dry ingredients into wet ingredients
Peel and slice the apples
Fold apples into the batter
Prepare the almond streusel topping by mixing flour, granulated sugar, brown sugar, cinnamon, and salt
Stir in melted butter until mixture is crumbly
Fold in sliced almonds
Pour cake batter into prepared pan
Top with almond streusel mixture
Bake until golden and a toothpick inserted in the center comes out clean
Cool and dust with powdered sugar if desired
