To Prep: Thoroughly grease your pan with shortening. Sprinkle flour on top and shake pan to coat all of the shortening. Do NOT preheat the oven.
Whisk together flour and baking powder in a large bowl.
In a separate large bowl, beat the butter, shortening, and sugar until creamy. Mix in any flavorings.
Alternate adding the flour and eggs into the butter mixture. Mix until smooth.
Spoon batter into the prepared pan and smooth the top. Put into the cold oven and set the temperature to 325°F. Bake for 1 hour, 30 minutes (my cake was done by 1 hour and 20 minutes, so check a little early). When done, the top will be lightly browned and a little cracked.