Chocolate-Cinnamon Coffee Cake

• 1/2 cup (1 stick) unsalted butter, room temperature, plus more for pan
• 1/2 cup blanched hazelnuts, chopped
• 2 ounces bittersweet chocolate, chopped
• 3/4 teaspoons ground cinnamon
• 1 cup sugar, divided
• 2 cups all-purpose flour
• 3/4 teaspoons baking powder
• 1/2 teaspoons baking soda
• 1/4 teaspoons kosher salt
• 1 teaspoon vanilla extract
• 2 large eggs
• 1 cup plain whole Greek yogurt

1. Preheat oven to 350u0b0F. Butter 8" square baking pan; set aside. Toss hazelnuts, chocolate, cinnamon, and 1/4 cup sugar in a bowl.
2. Whisk flour, baking powder, baking soda, and salt in a medium bowl. Using an electric mixer on high speed, beat butter and remaining 3/4 cup sugar in a large bowl until light and fluffy, about 3 minutes. Beat in vanilla. Add eggs one at a time, beating to blend between additions and occasionally scraping down sides of bowl. With mixer on low speed, add dry ingredients in 3 additions, alternating with yogurt in 2 additions, beginning and ending with dry ingredients.
3. Pour half of batter into prepared pan and smooth top; top with half of hazelnut mixture. Spoon remaining batter over and smooth top; top with remaining hazelnut mixture. Bake cake until top is golden brown and a tester inserted into the center comes out clean, 40-45 minutes. Transfer pan to a wire rack; let cake cool in pan before turning out.
4. DO AHEAD:

unsalted butter, blanched hazelnuts, bittersweet chocolate, ground cinnamon, sugar, flour, baking powder, baking soda, kosher salt, vanilla, eggs, greek yogurt

Taken from www.epicurious.com/recipes/food/views/chocolate-cinnamon-coffee-cake-51193740 (may not work)