• Preheat the oven to 350 degrees Fahrenheit. Grease a muffin tin.
• Roll the pie crusts out on a lightly floured counter top. 1 pie crust
• Cut 3.5 inch circles into the pie crust with a round cookie cutter, or top of a cup, jar, etc. Roll the circles out slightly to make them 4 inches in size.
• Place each circle into the opening of a greased muffin pan. Press down into the bottom of the pan. Place pan into the fridge until needed.

For the Berry Mixture:

• In a medium bowl, combine the berries, granulated sugar, cornstarch, and lemon juice. 2.5 cups mixed berries, 1/4 cup granulated sugar, 2 TBS cornstarch, 1 tsp lemon juice
• Place bowl into the fridge until needed.

For the Streusel Topping:

• Add the oats, brown sugar, and all purpose flour to a small bowl and whisk together. 1/3 cup old fashioned oats, 3 TBS brown sugar, 3 TBS all purpose flour
• Cut in the butter, using a pastry cutter, or two forks until the mixture is crumbly, with some pea sized pieces. 3 TBS unsalted butter

For Assembling the pies:

• Scoop about 3-4 TBS of the berry mixture into each pie crust, filling them evenly.
• Sprinkle the streusel topping evenly over the top.
• Bake the mini pies for about 20-30 minutes, until the crust is golden brown, and the berries are bubbling.
• Let the pies cool for about 10 minutes in the pan, then transfer them carefully to a cooling rack to cool to room temperature, and serve.