- Yield:Makes one 8- by 8-inch cake
- Active time: 15 minutes
- Total time:50 minutes
- 3 tablespoons room temperature butter
- 2 cups (10 ounces) all-purpose flour
- 1 teaspoon baking soda
- pinch of salt
- 1/2 cup brown sugar plus 1 tablespoon brown sugar, divided
- 2 tablespoons vegetable oil
- 1/2 teaspoon vanilla
- 1/4 cup Grand Marnier
- 2 eggs, beaten
- 1 cup Greek yogurt
- 1 cup blueberries
- 2/3 cups chopped walnuts, divided
- 1/4 teaspoons ground cinnamon
Adjust and oven rack to the center position and preheat oven to 375°F. Using 1 tablespoon of butter, grease an 8-by 8-inch baking pan.
In a large bowl whisk together flour, baking soda, and salt. In a separate bowl cream 1/2 cup brown sugar, vegetable oil, remaining 2 tablespoons butter, and vanilla with a wooden spoon until light and fluffy, about 4 minutes. When well mixed add Grand Marnier, eggs, and Greek yogurt and mix until well combined.
Add flour mixture to sugar mixture in two additions making sure everything is fully incorporated in between. Divide dough in half.
Press half of the dough into the bottom of the greased baking pan. Spread blueberries over dough, then mix 1/3 cup of chopped walnuts with ground cinnamon and spread over the blueberries and cover with remaining dough. Mix remaining nuts with remaining tablespoon brown sugar and spread over the top.
Place in the oven and bake until a toothpick inserted in the center comes out with just crumbs attached, about 25 minutes. Let cool 5 to 10 minutes and serve with butter.