Add the flour, brown sugar, and chopped almonds to a large mixing bowl and mix until well combined.
Cube the cold butter into small pieces and cut it into the mixture with a pastry blender or a fork until it resembles coarse crumbs. Transfer to the refrigerator until ready to use.
To make the cake:
Preheat the oven to 350°F. Spray a 9-inch springform pan well with non-stick cooking spray. Set aside.
In a large mixing bowl, mix together the 2 cups of flour, baking powder, baking soda, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl using a hand-held mixer, beat the butter and granulated sugar until light and fluffy.
Mix in the eggs one at a time until fully incorporated. Add in the vanilla and almond extract and continue mixing until well combined, scraping down the sides of the bowl as needed.
With the mixer on low, add the flour mixture in three parts alternating with the buttermilk (starting and ending with the flour) and mix until combined. Make sure not to over mix the batter.
Add the raspberries to a small mixing bowl and toss with the two teaspoons of flour until well coated. Gently fold the raspberries into the batter.
Scoop the batter into the prepared springform pan and smooth it out evenly. Remove the crumb topping from the refrigerator and sprinkle it evenly over the top.
Bake at 350°F for 45-55 minutes (mine is usually perfect at 50 minutes) or until a toothpick inserted into the center comes out clean. If needed, cover loosely with foil around the 40-minute mark to prevent the top from becoming too dark.
Remove the cake from the oven and cool on a wire rack for at least 20 minutes before releasing it from the springform pan. Slice and enjoy!
Notes
Storage instructions: Crumb cake is best served the same day it is prepared. Cover tightly and store at room temperature for 1-2 days.