Coffeecake is a beloved morning treat for good reason. This Cinnamon Streusel Yogurt Coffeecake is moist, tender, and layered with cinnamon filling. The topping is a wonderfully crispy and spiced streusel. Hello, Morning.
Preheat the oven to 350°F. Lightly grease a 9" x 13" pan and set aside.
Make the topping: whisk together all topping ingredients except cold butter. Cut in the cold butter using a pastry cutter or clean fingers. Mixture should resemble wet sand, with some small clumps throughout. (Should not be like dry sand - if it's too dry, add more cold butter) Cover and chill.
Make the filling: mix together the brown sugar, cinnamon, and cocoa powder. Set aside.
Make the cake: In a large bowl, beat together the butter, salt, sugars, baking powder, and vanilla until well combined and smooth. Add the eggs one at a time, beating well after each addition.
In a separate bowl, whisk together yogurt and milk until well combined. You don't need to whisk out all the lumps.
Add the flour to the butter mixture, alternating with the yogurt mixture, beating gently to combine.
Spread half the batter (about 3 cups) into the prepared pan(s), spreading all the way to the edges. Sprinkle the filling evenly over the batter. Spread the remaining batter atop the filling. Sprinkle the cold streusel topping over the batter in the pan.
Bake until toothpick inserted into the center comes out almost clean, with few tender crumbs attached - about 50-55 minutes.
Allow cake to cool for 30 minutes before cutting and serving. Leftovers can be covered and kept at room temperature.
If desired, whisk together simple glaze ingredients and drizzle over top of cake.