In a heavy bottomed saucepan melt together butter and brown sugar. Add 2 1/2 cups half and half. Cook over medium heat for 5 minutes, or until mixture bubbles along the edge.
Meanwhile, whisk together remaining 1/2 cup half and half, cornstarch and eggs. Add 1/4 cup hot liquid to temper. Stream tempered eggs into saucepan whisking constantly.
Cook over medium heat until mixture begins to thicken, whisking constantly. Lower heat to simmer and allow to bubble while whisking for 1-2 minutes longer.
Remove from the heat, add vanilla. Mix well. Pour into crust. Chill while you make the meringue.
Meringue: Using an electric mixer beat together egg whites and cream of tarter until foamy. Gradually add sugar beating until stiff glossy peaks form.
Remove pie from fridge. Spread meringue on to pie taking it to the edge.
Preheat oven to 350°F. Bake pie for 10-12 minutes or until peaks are lightly browned, turning as needed for even browning.
Chill for 8 hours or overnight before slicing. Store leftovers chilled.