Stir wet mix into dry mix until combined. Be careful not to overmix.
Fill muffin cups to 3/4 full.
For cream cheese filling: Whisk all ingredients together until smooth.
Put filling into a quart ziplock and snip one corner tip off. (only snip a small 1/4 inch corner.) Stick the tip into the top of each muffin cut and squeeze approximately a tbsp of the cream cheese filling into the muffin.
Bake for about 20 mins. I always check mine around 18 minutes for doneness.