Thaw out puff pastry for 40-50 minutes on a cutting board

Add blueberries to a small bowl and add in 1 T sugar, flour and salt. Mix to coat blueberries.

Once puff pastry is thawed, open it up and lay it flat. Cut each sheet into 9 squares.

Place one of the puff pastry squares in each muffin tin section, and press it in. Use a fork to add small holes to the center of each puff pastry.

Add a spoonful of blueberry mix to each section, about half full of blueberries.

Add a butter cube to each tart and sprinkle with sugar.

Bake at 400 degrees for 15-16 minutes or until edges are golden brown. Cool for 15 minutes.