I thought that recipe looked familiar, worked fine for me... A few things you can try:
( I am a bit confused though... I have never had a chemically levened cake fall on me, air-levened cakes all the time though
)
A stronger flour
Beat for a longer period of time.
What pans are you baking in and how much batter is going in them. Some cakes collapse under their own weight despite levening (this may be where a stronger flour may help)
Use shortening instead of butter (GASP! Its the fat of choice in traditional High-Ratio)
Dumb question but I have to ask (many students have been guilty of this in the past) are you weighing the ingredients on a scale or using measuring cups? I weigh everything nowadays... even water for breads.
If all of that fails
Cake Flour 3 7/8 oz
Cocoa Powder 5/8 oz
Salt 1/2 tsp
Baking Powder 1 tsp
Baking Soda 1/2 tsp
Evil Shortening 2 1/4 oz
Sugar 5 1/8 oz
Milk #1 2 1/2 oz
Vanilla 1 1/2 tsp
Milk #2 2 oz
Eggs 2 1/2 oz
Sift Dry
Cream shortening with dry for two minutes
Scrape
Cream another two minutes
Add Milk #1 and Sugar
Mix 3 minutes
Scrape
Add Milk # 2 and eggs alternating
Scrape
Mix another 5 minutes
Bake 335 for 30-35 minutes. Makes 1 8in cake.
