My girlfriend makes the best pound cakes. She finally shared the recipe, but I can't seem to get it to not collapse. It calls for 6 eggs, 1 c milk, 3 1/3 c flour, 1/2 tsp baking powder, 1/4 tsp salt, 3 sticks salted butter, 3 tsp lemon extract, 3 c sugar. I cream butter/sugar, add eggs one at a time. I use White Lily flour (I sift but don't re-measure after sifting). I alternate the dry ingredients & milk, then add extract. Baked at 350 degrees for 1 hour. It rises and spills out the pan (I measured very accurately). I was told not to overbeat or it will not have the firmness, but fluffy instead. Alas, I never make it that far because it collapses before I can take it out. I successfully made this same cake only once before and felt so confident I decided to try, but the last 2 times I failed. Don't know what I'm doing wrong. Help!