Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, and salt in a large bowl. Cut in shortening with a pastry blender or 2 knives until mixture resembles coarse meal; make a well in center of mixture. Combine hot water and dry milk, and add to flour mixture. Stir until blended. Cover and let rest 20 minutes.
Divide dough into 18 equal portions, shaping each portion into a ball (cover remaining dough to prevent drying). Roll each ball into a 7-inch round. Heat a cast-iron skillet over medium-high heat. Cook each round 1 minute on each side or until lightly browned.