Heat oven to 375°F. Line a 12-cup muffin pan with liners and lightly coat with spray.
Stir topping: Mix flour, brown sugar, granulated sugar, cinnamon, and salt. Drizzle in melted butter and toss until clumpy. Chill.
Beat filling: In a bowl, blend cream cheese, sugar, vanilla, and egg yolk until smooth and creamy. Set aside.
Toss blueberries with 1 tbsp flour to lightly coat; set aside.
Whisk dry batter ingredients: flour, sugar, baking powder, salt, and lemon zest in a large bowl.
Whisk wet batter ingredients: milk, sour cream, egg, melted butter, and vanilla until combined.
Combine wet with dry and fold just until no dry spots remain. Gently fold in blueberries.
Fill muffin cups halfway with batter. Dollop a rounded teaspoon of cheesecake filling in the center of each.
Cover with more batter to about 3/4 full. Crumble topping evenly over each muffin; sprinkle coarse sugar if using.
Bake 20–23 minutes, until golden and a tester shows moist crumbs. Cool 5 minutes in pan, then transfer to a rack to finish cooling.