Preheat oven to 425°F. Spray tin with non-stick spray or line with muffin liners.
Gently toss together flour, baking powder, salt, and cinnamon.

In separate bowl, whisk together eggs and sugar until combined. Fold wet ingredients into dry, mix by hand. Avoid over-mixing. Fold in blueberries.

Pour into tins, filling to the top. Bake 425 for 5 minutes. Reduce to 375°F, bake for another 25 minutes.

Store at room temperature up to 5 days, or freeze up to 3 months.