Mix flour, sugar, salt and baking powder in a large bowl.
In a measuring cup, add oil (or bacon grease, if using), beaten egg and top off with milk until mixture equals 1 cup. Then add additional 1/2 cup milk.
Add wet ingredients from Step 2 to dry ingredients from Step 1 and combine. Fold in bacon and blueberries.
For cinnamon crumb topping: mix sugar, flour, butter and cinnamon in a separate bowl.
Prepare muffin tray(s) by lining 16 muffin cups with liners. Fill up about 2/3 full with muffin mixture. Top each muffin mixture with 1 or 2 tsp. of cinnamon crumb mixture.
Bake in oven for 20-25 minutes or until toothpick comes out clean.