Velvety Vanilla Buttermilk Pie

Ingredients

• 1 tbsp vanilla extract
• 1/2 cup unsalted butter, softened
• 2 tbsp all-purpose flour
• 1/8 tsp salt
• 3 large eggs, room temperature
• 1 pre-made pie crust
• 1 cup buttermilk
• 1 tbsp cornstarch
• 1 1/2 cups granulated sugar