Preheat oven to 400°.
To prepare muffins, lightly spoon flours into dry measuring cups; level with a knife. Combine 1 1/2 cups all-purpose flour, whole wheat flour, oats, granulated sugar, baking powder, baking soda, and salt in a large bowl, stirring with a whisk.
Make a well in center of mixture. Combine yogurt, milk, oil, vanilla, and egg, stirring with a whisk. Add yogurt mixture to flour mixture; stir just until moist.
Fold in blueberries. Spoon 2 rounded tablespoons batter into each of 30 muffin cups coated with cooking spray.
To prepare streusel, combine 1/4 cup all-purpose flour, almonds, brown sugar, and butter.
Sprinkle evenly over batter. Bake at 400° for 15 minutes or until muffins spring back when touched lightly in center. Cool in pans 10 minutes on a wire rack; remove from pans. Serve warm or at room temperature.