For the nut & oat crumble
- 2/3 cup raw walnuts or pecans, finely chopped
- 1/3 cup oats
- 2 tablespoons gluten-free flour, like Bob’s Red Mill or Cup 4 Cup
- 1/4 cup brown sugar
- 1 teaspoon Peni Miris Cinnamon
- 1/4 teaspoon salt
- 1/4 teaspoon baking powder
- 3 tablespoons unsalted butter, softened
For the coffee cake
- 1/2 cup (1 stick) unsalted butter, softened, plus more for greasing
- 1/2 cup brown sugar
- 1/4 cup white sugar
- 2 eggs
- 1/2 cup low-fat buttermilk
- 1 1/2 teaspoons vanilla extract
- 1 1/2 cups gluten-free flour, like Bob’s Red Mill or Cup 4 Cup
- 1 1/2 teaspoons baking powder
- 1/4 teaspoon baking soda
- 1/4 teaspoon Anamalai Nutmeg
- 1/4 teaspoon ground Anamalai Mace
- 3/4 teaspoon kosher salt
- 1/4 cup Anamalai Cacao
- 2 teaspoons Peni Miris Cinnamon
- Preheat the oven to 350°F. Grease an 8x8-inch baking pan with butter, line with parchment paper and set aside.
- For the streusel, combine all the ingredients except for the butter in a medium bowl and mix well. Add the softened butter and, using your fingers, work the butter into the dry ingredients until a crumble forms. Set aside.
- To make the coffee cake batter, place the butter, brown sugar and white sugar in a large bowl. Using an electric mixer on medium high, cream the butter and sugar until light and fluffy, about 3–4 minutes. Beat in the eggs one at a time, then add the buttermilk and vanilla extract and beat until smooth, about 30 seconds to 1 minute.
- Add the gluten-free flour, baking powder, baking soda, nutmeg, mace and salt to the wet ingredients and beat on medium low until the dry ingredients are completely incorporated, about 1 minute. Transfer half of the batter to a medium bowl, add the cacao powder and gently fold into the batter. Add the cinnamon to the other half of the batter and gently fold in until incorporated.
- Scoop one spoonful of the chocolate batter and place one spoonful in each corner of the pan and then one in the center of the pan. Fill the empty spaces with spoonfuls of the cinnamon batter. Drag a toothpick or a skewer through the batter to slightly swirl the two without over mixing them. Sprinkle the oat-nut crumble evenly over the top, gently pressing it into the batter.
- Bake until a toothpick comes out clean from the center of the coffee cake, about 32–35 minutes. Let cool to warm or room temperature before serving.