Sift flour, baking powder, and salt into a bowl. Put butter and 1 1/2 cups sugar in the bowl of an electric mixer fitted with paddle attachment. Mix on medium speed until pale and fluffy, about 3 minutes. Mix in eggs. Reduce speed on low, gradually mix in flour mixture.
Stir together cinnamon and 2 T sugar in a small bowl. Shape dough into twenty 1 3/4 inch balls; roll in cinnamon sugar. Space 3 inches apart on baking sheets lined with parchment paper.
Bake cookies, rotating sheets halfway through, until edges are golden, 12-15 minutes. Let cool on sheets on wire racks. Cookies can be stored b/w layers of parchment in airtight containers at room temperature for up to 3 days.