Egg-Free Blueberry Coffee Cake with Pistachio Crumbs

1. Preheat the oven to 350°F. Prepare an 8” square pan with a parchment sling and grease.
2. To make the crumbs: In a medium bowl, whisk together the flour, masa harina, sugars, and salt. Add the butter and vanilla; toss to combine. Using a bowl scraper, a fork, or your fingers, work in the butter until crumbs form and no dry spots remain. Add pistachios.
3. To make the cake: In a small bowl, combine the masa harina, water, and vanilla. Stir until smooth and crumbly, then set aside to hydrate.
4. In a bowl of a stand mixer, combine the flour, sugar, baking powder, salt, and baking soda. Add the butter and mix at low speed using an electric hand mixer or the flat beater on a stand mixer, until the mixture looks sandy, about 1 to 2 minutes.
5. Beat in the JUST eggs, then mix until no dry spots of flour remain. Stop the mixer and scrape the bowl and beater(s) as needed; the mixture will be thick.
6. Add the hydrated masa harina and yogurt all at once before starting to mix. Continue to stir until the batter is smooth. Stop to scrape the bowl and then mix again at low speed for 1 minute.
7. Use a spatula to gently fold in 1/4 cup (37g) of the blueberries & lemon zest into the batter by hand; try to keep the blueberries whole.
8. To assemble and bake the coffee cake: Transfer the batter into the prepared pan and spread it evenly all the way to the edges. (Note: The baking time and temperature are not provided in the original content after this step. Typically, coffee cakes bake at 350°F for 35-50 minutes, or until a toothpick inserted into the center comes out clean.)