How to Make It
Preheat oven to 400°. Whisk together 4 cups baking mix, 3/4 cup sugar, and 1/8 tsp. cinnamon in a large bowl; reserve 2 Tbsp. mixture. Make a well in center of remaining sugar mixture in bowl.
Whisk together mayonnaise and next 4 ingredients; add to sugar mixture in large bowl, stirring just until moistened.
Toss blueberries with reserved 2 Tbsp. sugar mixture. Carefully fold blueberries into batter. Spoon into a lightly greased muffin pan, filling almost completely full.
Stir together 1 Tbsp. melted butter and remaining 2 Tbsp. baking mix, 3 Tbsp. sugar, and 1/8 tsp. cinnamon until mixture is crumbly; sprinkle over batter in pan.
Bake at 400° for 18 to 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 5 minutes. Remove from pan to wire rack, and cool 10 minutes.