Gradually add bread flour to the egg and milk mixture, whisking JUST enough to thoroughly combine and eliminate most lumps. BE CAREFUL not to overmix. Add remaining 1/4 cup milk, and whisk JUST enough until smooth and fully combined. Let the batter stand at room temperature while you prepare your mise en place. Put the popover tins included in your kit on a baking sheet, and place in the oven to heat. Pull the preheated baking pan with popover tins from the oven. Please be careful; the pan and tins will be very hot. Divide the batter evenly among the 4 tins; each should be a little less than 1/2 full. Carefully return tins to the oven, and bake 15 minutes. Without opening the oven door, reduce heat to 350° F, and bake an additional 15 minutes. When the timer goes off, turn the oven off but DO NOT open the door.