Whisk 2 cups plus 2 tablespoons flour, yeast, sugar, and salt in a large mixing bowl. Combine water and milk in a separate bowl and quickly whisk the milk mixture into the dry ingredients until batter is thick and smooth. Cover with a towel and let rise in a warm place until spongy, about 1 hour. Stir dough to reduce sponginess.

Place a rack into the oven and preheat to 150 degrees F (65 degrees C).

Spray a skillet and round metal open-top cookie cutters or crumpet molds with cooking spray. Heat skillet over medium-low heat, place the metal cutters or molds into the skillet, and let the molds heat up. Spoon batter into the molds, filling them about halfway. Let the crumpets cook until the bottoms are browned, the tops appear nearly dry, and popped bubbles appear on top, about 5 minutes.

Use tongs to lift molds out of the pan; remove molds from the crumpets. Flip and return crumpets to skillet to cook the other sides until browned, 1 to 2 more minutes. Repeat with remaining dough. Keep cooked crumpets warm on rack in the preheated oven while you cook remaining crumpets.