French Silk Chocolate Pie II

1 cup butter
1 1/2 cups white sugar
4 tablespoons unsweetened cocoa powder
2 tsps vanilla extract
4 eggs
1 ( 9 in) pie crust, baked

1. Cream butter and sugar. Blend in cocoa and vanilla. Beating at high speed, add on e egg and beat until thoroughly incorporated. Repeat with each remaining egg. Keep whipping until fluffy. spread in cooked pie shell of choice and keep refrigerated