Preheat the oven to 375 degrees F.
Place the 2 3/4 cups flour, baking powder and salt in a bowl and whisk to combine. Place the butter, 1 1/4 cups granulated sugar and brown sugar in a second bowl and beat until light and well combined, and then mix in the eggs and vanilla. Mix in the flour mixture until well combined.
Line 2 baking sheets with parchment paper. Spread the sugar/cinnamon mixture on a plate. Roll a piece of dough into a 1 1/2 inch ball. Roll the ball in the cinnamon sugar, thoroughly coat it, and then set on a baking sheet. Repeat with the remaining dough, leaving a 2" space between each cookie. Bake the cookies, one sheet at a time, for 15 minutes.
Sprinkle the hot baked cookies with any remaining cinnamon sugar on the plate. Cool the cookies on a baking rack.