Gluten Free Blueberry Coffee Cake with Pecan Streusel

Make the streusel:
2 In a medium bowl, stir together the almond flour, pecans, oats, oat flour, tapioca flour, sugar, salt, cinnamon, and nutmeg. Stir in the butter until large clumps form. Set aside.
Make the cake:
5 Position a rack in the center of the oven and preheat to 350º.
6 Rub a 9-inch round cake pan or springform pan with butter and line the bottom and sides with a piece of parchment paper.
7 In the bowl of a stand mixer fitted with the paddle (or a bowl with a wooden spoocream the butter and sugar together on medium speed until light and fluffy, 3 - 4 minutes, scraping down the sides of the bowl once or twice.
8 Add the eggs one at a time, beating until combined after each addition. The mixture may look broken.
9 Meanwhile, sift the sweet rice, sorghum, oat, and tapioca flours into a medium bowl along with the baking powder, baking soda, and salt into a medium bowl.
10 Stir together the sour cream and vanilla.
11 With the mixer on low, add half of the flour mixture, mixing until combined. Add the sour cream mixture, beating until combined. Add the remaining flour mixture and beat until combined, then increase the mixer to medium speed and beat until the batter is light and fluffy, 20 seconds longer. (Wheat based batters shouldn’t be beaten vigorously, but here it helps aerate the gluten free batter.) Give the batter a final fold with a rubber spatula to make sure it is homogenous, scraping down the sides and bottom of the bowl and beater.
12 Spread a little more than half the batter in the bottom of the pan. Sprinkle the berries evenly over the batter in a single layer. Sprinkle the lemon zest over the berries. Dollop the remaining batter over the berries and spread to cover. Sprinkle the streusel over the cake, squeezing it into almond sized clumps if necessary. Tuck a few extra blueberries into the streusel.
13 Bake the coffee cake for 45-55 minutes until it is golden brown and a toothpick inserted near the center comes out clean or with a few crumbs. Let cool completely or until just warm.
14 Remove the cake from the pan and cut it into wedges. Dust with powdered sugar and serve slices with a drizzle of blueberry glaze.
15 The coffee cake is best the day it's baked when the streusel is crisp, but leftovers keep well for up to 3 days in the refrigerator.