Baking Mix Blueberry Muffins

I tried to make blueberry muffins the way I remembered them from my childhood, but even using those recipes, they seemed dry, and not the way I expected. Modern recipes were too much like a yellow cupcake with blueberries in them. I eventually tried a recipe off of a box of biscuit and baking mix, and it was pretty much exactly what I wanted.
Of course I lost that recipe.
I later found one on Food.com that is probably identical. Being who I am, I've modified it a bit. Here's my version:

Baking Mix Blueberry Muffins
2 Cups Bisquick, Jiffy, or other biscuit and baking mix
1/3 Cup Sugar
2/3 Cup milk
1/4 Tsp vanilla (or 1 Tsp vanilla sugar added to sugar before measuring)
2 Tablespoons vegetable oil
1 Egg
3/4 to 1-1/2 Cup fresh or frozen blueberries
Preheat oven to 350 degrees. Spray 12 muffin pan with non-stick cooking spray, or line with paper baking cups, or line with parchment paper. Mix together all ingredients except blueberries until moistened. Batter will be lumpy. Fold in blueberries. Divide blueberries evenly into the muffin cups and bake 15-20 minutes until lightly browned around edges. Cool briefly and remove from muffin tins. Serve while warm.