Preheat oven to 350°F. Grease and flour a Bundt pan.
PREPARE THE STREUSEL:
In a medium bowl, combine chopped nuts, flour, brown sugar, cinnamon and salt. Add chilled butter and mix together with your fingers until it forms a crumble. Set aside.
PREPARE THE CAKE BATTER:
In a stand mixer fitted with a paddle attachment, cream together softened butter, granulated sugar and brown sugar on medium-high speed until light and fluffy (about 4 minutes). Add eggs, one at a time, beating until completely combined. Mix in sour cream and vanilla extract.
In a separate bowl, sift together flour, baking powder, baking soda and salt. While the mixer is running on low speed, gradually add the dry ingredients to the wet ingredients. Mix just until combined – do not overmix.
Sprinkle half of the streusel mixture in the prepared pan. Top with half of the batter. Add remaining streusel, and then remaining batter.
Bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean. Cool cake in pan on a wire rack 15 minutes; invert cake onto wire rack, and let cool completely before glazing (about 2 hours).
PREPARE THE GLAZE:
Combine confectioners’ sugar, milk and vanilla in a bowl. Whisk until smooth. If the glaze seems too thin, add more powdered sugar. If the glaze seems too thick, add a small amount of milk.
Drizzle glaze over the top of the cool cake.
Notes
Wrapped tightly, the cake will last at room temperature for up to 2 days. It does not need to be refrigerated.
Store the cake in an airtight container in the refrigerator for up to 1 week.
If you’re enjoying cake a day (or more) later, reheat the leftovers to give the slices a nice, soft texture. Just loosely cover an individual slice and microwave for 10-15 seconds (or until warm).
To Freeze: Allow the cake to cool completely. Do not glaze. Wrap tightly with a layer of plastic wrap and then a layer of foil. Store in the freezer for up to 3 months. Thaw on the counter overnight. Once the cake is completely thawed, drizzle with icing and serve!