This coffee cake is for the person who likes to eat the crumbly streusel right off the top. Scented with freshly grated orange zest and a touch of almond extract, this sweet, pillowy cake is topped with an excessive amount of buttery, nutty crumble that borders on savory. It will seem like a lot of streusel, but trust me – you will want every last bite of it! When sprinkling your brown sugar filling, be sure to get all the way to the edge of the pan so you get a nice line in the middle of your cake slice. Also, it will seem like a big pan for the amount of batter, but it will rise considerably. Hot tip: use a tube pan with a removable bottom to make unmolding your coffee cake easier.
Make the crumb topping In a medium bowl, mix the flour with the almonds, brown sugar, cinnamon and salt. Using your hands, work in the butter until the dry ingredients are completely incorporated into the butter and large, marble-size clumps form when pinched. Refrigerate while you prepare the cake.
Make the filling In a small bowl, combine all ingredients.
Make the cake Preheat the oven to 350 and butter and flour a 9-inch tube pan. In a medium bowl, sift the flour with the baking powder, baking soda and salt.
In the bowl of a stand mixer fitted with the paddle or in a large bowl and using a hand mixer, beat the butter with the granulated sugar at medium speed until light and fluffy, about 2 minutes. Beat in the eggs, one at a time, then add the orange zest and vanilla and almond extracts. Beat in the dry ingredients at medium speed in three additions, alternating with the sour cream and beginning and ending with flour. Continue to beat until smooth and just combined.
Spoon half of the batter into the prepared tube pan. Give the pan a few firm taps on a work surface, then smooth the top using the back of the spoon. Sprinkle the filling evenly across the batter. Dollop the remaining batter on top and smooth with the back of the spoon. Remove the crumble from the refrigerator and break into marble-size pieces. Scatter the crumb topping evenly over the cake.
Set the tube pan on a rimmed baking sheet and transfer to the oven. Bake until the cake is golden brown and a toothpick inserted in the center comes out clean, about 55 minutes. Transfer to a wire rack and let cool completely before unmolding.
Before serving, make the glaze In a medium bowl, whisk the confectioners’ sugar with the milk until smooth. Transfer the unmolded cake to a platter or cake stand, then drizzle all over with the glaze. Slice the cake and serve.
MAKE AHEAD The cake can be covered and stored at room temperature for up to 3 days.