Step 1Heat the oven to 350 degrees. Grease a 13x9-inch baking pan or grease and lightly flour 2 (8-inch) round baking pans; set aside.
Step 2Combine the flour, baking powder, cinnamon, baking soda, nutmeg, cloves and ginger; set aside.
Step 3Beat the butter and shortening in the bowl of an electric mixer on medium to high speed for 30 seconds. Add the sugar and vanilla; beat until well combined. Add the eggs, one at a time, beating well after each. Combine the pumpkin and buttermilk, stirring well to blend. Add the flour mixture and the pumpkin and milk mixture alternately to the beaten mixture, beating on low speed after each addition just until combined. Pour into the prepared pan(s).
Step 4Bake the cake until a toothpick comes out clean, 35 to 40 minutes for a 13x9-inch pan or 30 to 35 minutes for the round pans. Place the 13x9-inch cake pan on a wire rack; cool thoroughly. Or, cool the layer cakes in the pans on wire racks for 10 minutes. Remove the layer cakes from the pans. Cool thoroughly on the racks. Frost with Penuche Frosting.
Step 1Melt the butter in a saucepan over medium-low heat; stir in the brown sugar. Cook and stir until bubbly. Remove from the heat. Add the milk; beat vigorously with a wooden spoon until smooth. Add the powdered sugar; beat by hand until the frosting is easy to spread. Use immediately.