Place a rack in the center of your oven and preheat the oven to 375 degrees F. Lightly coat a 9-inch springform pan with non-stack spray and set aside.
Make the crumb topping: In a medium bowl, stir together granulated sugar, whole wheat pastry flour, cinnamon, and salt. Scatter the butter pieces over the top, then with a fork, pastry blender, or your fingers, work the butter into the dry ingredients until moist crumbs form. Stir in the sliced almonds until evenly distributed and set aside.
Make the berry coffee cake: In a stand mixer fitted with the paddle attachment or a large mixing bowl, beat together the sugar and butter until light in color and fluffy, about 3 minutes. Beat in the almond extract until incorporated.
In a medium bowl, stir together the whole wheat pastry flour, all purpose flour, baking powder, and salt. In a small bowl or measuring cup, whisk together the almond milk and egg.
Add one third of the dry ingredients to the butter mixture, mix on low speed just until combined, then add half of the wet ingredients and mix gently to combine again. Continue alternating the dry ingredients and wet ingredients as follows, mixing between each addition: the second third of the dry, the remaining wet, then the final third of the dry ingredients. By hand, gently fold in the berries, stirring just until barely blended.
Spread the cake batter into the prepared pan and smooth the top, then sprinkle the crumb topping mixture evenly over the top.
Bake the cake for 40-50 minutes, until the crumbs are golden and a toothpick inserted in the center comes out clean.
Place the pan on a wire rack and let cool for 10 minutes in the pan. Gently run abutter knife around the edge of the cake to loosen it, then remove the sides of the pan.
While the cake cools, prepare the glaze: Whisk together the powdered sugar, vanilla extract, almond extract, and milk until smooth. Add more milk/powdered sugar to reach a thicker or thinner consistency as desired. Drizzle the glaze over the top of the cake. Serve warm or at room temperature.
*INGREDIENT NOTE: I highly recommend whole wheat pastry flour for this recipe. It makes the cake extra fluffy and tender, while providing the benefits of whole grains, and you cannot taste it at all! If you do not have whole wheat pastry flour, I recommend substituting regular all-purpose flour. Regular whole wheat flour will work in the recipe, but will result in a heavier texture and more pronounced "wheaty" taste.
TO STORE: Leftover coffee cake will keep at room temperature for up to 3 days. Bake up to 1 day ahead and (if possible) glaze just before serving.
TO FREEZE: You can freeze this cake in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator.
MAKE AHEAD: Pour the batter into the prepared pan, but don't sprinkle the crumbs on top. Cover the pan, and refrigerate. Separately, prepare and refrigerate the crumb topping. The next day, uncover the pan, sprinkle the crumbs on top, and bake for 55 to 65 minutes, or until a toothpick inserted into the center of the cake comes out clean.