Preheat oven to 325 degrees F.
Sift cake flour and measure, sift all-purpose flour and measure.
Sift both flours together, with baking powder and salt. Gently whisk, or place in mixer to aerate more.
Add sugar to dry ingredients. Mix to combine.
Combine melted butter and oil. Mix gently to combine.
Add vanilla extract to butter/oil mixture.
Mix butter and oil into dry ingredients.
Add eggs and yolk one at a time, mixing well after each addition.
Slowly add evaporated milk. Mix to combine.
Portion into mini-cupcake tins or regular size cupcake tins. Fill to about 3/4 full, or 2/3 for a slightly shorter rise.Tap pans gently to release air bubbles.
Bake 13-14 minutes for mini-cupcakes, or 15-20 minutes for regular size cupcakes, or until toothpick comes out with just a few crumbs.
Remove pans from oven and let rest for five minutes. Gently turn out cupcakes onto wire rack to cool.