Let pie thaw at room temperature for 30 to 45 minutes. Preheat oven to 350° F.
In a small saucepan, melt the stick of butter over medium heat. Add 1/2 cup brown sugar, 1 1/2 tsp cinnamon, allspice, cloves and lemon juice. Stir until well blended and sugar is melted, about 3 minutes.
Make an X in the center of the top crust of the pie and fold back the crust. Pour the butter mixture evenly into the pie and then replace the crust. Leave 4 vent holes, sealing the rest of the pastry. (You may need to dampen your fingers to seal the pastry.) Bake for 30 minutes. Remove from the oven and set aside.
Reduce heat to 325° F.
Prepare topping. Grate frozen butter into a medium-size bowl. Toss the grated butter with flour, remaining sugars, remaining cinnamon and walnuts.
Carefully wrap an aluminum foil band around the edge of the pie, creating a lip to hold topping. Sprinkle topping evenly over pie.
Bake for 30 to 40 minutes. Let rest for 10 minutes then serve with ice cream, if desired.
NOTE: Butter must be frozen to grate properly. If the butter softens, you will end up with a gooey mess.Makes 4 Source: