Preheat oven to 180°C. Brush twelve 150ml-capacity Texas muffin pans with melted butter to lightly grease.
To make the crumble topping, place the flour in a bowl. Use your fingertips to rub the butter into the flour until the mixture resembles coarse breadcrumbs. Stir in the sugar and almonds.
Place the flour and sugar in a large bowl. Add the butter, milk and egg, and stir until well combined.
Spoon the mixture evenly among the prepared pans. Divide the blueberries evenly among the pans. Sprinkle over the crumble mixture. Bake in oven for 20-25 minutes or until a skewer inserted into the centres comes out clean. Set aside in the pans for 15 minutes to cool slightly.
Warm the custard following packet directions. Remove the muffins from the pans and divide among serving plates. Drizzle over the custard to serve.