Preheat oven to 350°F. Place butter in a 9x9 inch baking dish and put in oven while preheating to melt.
In a medium bowl, whisk together flour, sugar, and salt.
In a separate container, combine buttermilk, vanilla extract, and lemon extract. Pour wet ingredients into dry and stir just until combined. Don't overmix.
Remove pan with melted butter from oven. Pour batter over butter without stirring.
Spoon lemon pie filling evenly over batter. Do not stir.
Bake on middle rack for 55-60 minutes until top is deep golden brown and filling is bubbling around edges. Center may look slightly jiggly.
Let rest for 10 minutes before serving. Serve warm with ice cream or whipped cream if desired.