6tablespoonsunsalted butter, softened to room temperature
1/4cupplus 2 tablespoons granulated sugar
1/4cupplus 2 tablespoons brown sugar, packed
1large egg, room temperature
1 and 1/2teaspoonsvanilla extract
1 and 1/2cupsall purpose flour,spooned and levelled
3/4cupbuttermilk, room temperature
2-3medium to medium-large sized apples, pealed, cored and sliced to equal about 1 and 1/4 cups
1/2cupsalted caramel sauce for serving
Preheat the oven to 350F degrees. Butter a 9 inch spring-form pan and sprinkle the bottom with flour. Set aside.
For the streusel toss together the flour, sugars, cinnamon and salt for the streusel in a medium sized bowl. Cut in the cold butter using a pastry cutter or crumbling in the butter with your fingers. The mixture should be sandy.
In a large bowl with a stand or hand-held electric mixer. beat the butter and sugars on medium speed until light and fluffy (about 2 minutes). Add in the vanilla and egg and continue beating until combined (about 30 seconds).
In a separate medium sized bowl, whisk together the flour, baking powder, baking soda, salt & cinnamon for the coffee cake. Slowly add the flour mixture into the butter mixture, alternating with additions of the buttermilk while beating on low speed until combined. The batter will be very thick.
Scrape down the sides of the bowl and pour/spoon the batter into your prepared pan. Place the apple slices on top of the batter, followed by the streusel.
Bake in your preheated oven for 50-60 minutes until an inserted toothpick comes out clean. Mine took exactly 55 minutes. Allow the cake to cool for about 20 minutes in its pan. Then circle the edge of the springform pan with a thin knife, release the edges & continue cooling on a wire rack until completely cool.
Serve the cake with a drizzle of salted caramel sauce.