Classic Coffee Cake

0 In a medium bowl, whisk together brown sugar, flour, cinnamon, and salt. Stir in the melted butter and vanilla until you get big, clumpy crumbs. Set aside.
1 Grease and line an 8×8 or 9×9 square baking pan with parchment paper.
2 In a large bowl, cream softened butter and granulated sugar until light and fluffy (about 2–3 minutes). Add eggs one at a time, beating well after each. Stir in vanilla and sour cream.
3 In a separate bowl, whisk together flour, baking powder, baking soda, and salt. Add to the wet ingredients and mix until just combined—don’t overmix.
4 Pour the batter into the prepared pan and smooth the top. Gently press the crumb topping evenly over the batter. Don’t be shy—it’s a thick layer!
5 Bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean. If the top starts to brown too quickly, tent loosely with foil halfway through.
6 Let the cake cool for at least 20 minutes before slicing. Dust with powdered sugar if you want to get fancy.