Chiffon mini cakes deflating in center

[bimfi]

I am trying to make mini chiffon cupcakes. Although they come out fairly well, they all tend to deflate slightly when cooling. I have tried many different recipes, but they all seem to do the same thing. I have tried increasing the flour content a tad. I have also tried to decrease the liquid content a bit. I want it to have the light and fluffy texture but also maintain the slightly dome-like look when it first comes out of the oven. When I aerate the egg whites I try to keep the meringue at a medium peak, not a stiff peak. Most of the recipes I have used have the following ingredients: Flour, sugar, baking powder, salt, oil, milk and eggs (separated). I usually use jumbo eggs. Could it be that my egg volume is too much for the other ingredients? Any suggestions?

 

[chassis]

What is your most recent recipe? Precise amounts, not a generalized list of ingredients, including baking time and temp.

Potentials:
- protein matrix not set, insufficient eggs or baking time+temp insufficient
- oven temp too hot
- baking time too short
- elevation/altitude playing a role
- too much leavening
- too much liquid (oil, milk, water, egg)

 

[bimfi]

Most recent recipe: 6 Jumbo eggs, separated; 200 grams cake flour; 225 grams granulated sugar; 8 grams B. Powder; 2.5 grams salt; 90 grams oil; 150 grams milk; 1 T vanilla; 1/4 tsp cream of tartar. Yolks, oil, milk, vanilla whisked together. Dry ingredients sifted together then added to the yolk mixture and blended till smooth. Whites whipped with tartar, then sugar gradually added until medium peak. Whites folded into yolk mixture until all incorporated. two scoops placed in each brioche molds (this recipe makes 18 or 19 molds (Mamons).
Oven temp is set to 325F and baked for 28 to 30 minutes or until tops are a golden brown. Remove from oven and allow to cool. Recipe says to invert pans but then the tops will stick to wire rack when cooling. I do not invert molds.

 

[bimfi]

I just modified my existing recipe and used less eggs to see if this would make a difference. Made a half batch and the centers did not shrink. So, maybe this was part of the problem.

 

[chassis]

Photos?