Fill a bowl halfway with very hot tap water and gently add the eggs to warm them. When the water cools, carefully drain the eggs and cover them again with very hot tap water.
Meanwhile, in a heavy saucepan over medium heat, warm the milk until it feels warm to the touch. Remove from the heat.
Place the flour in a large bowl or a large measuring cup with a spout. Using a fork or whisk, beat in the milk, a little at a time to prevent the batter from forming lumps. Let the flour and milk mixture stand at room temperature for at least an hour.
After the flour and milk mixture has been standing for about 15 minutes, adjust the oven rack to the lower third position and place a baking stone on it. Preheat the oven to 475°F (246°C). (If you think your oven runs low, turn it to 500°F (260°C) as the oven needs to be quite hot.)
After the flour and milk mixture has stood for over an hour, place the popover pan in the oven on the stone to heat.
Separate 3 of the eggs, saving the whites and storing the yolks. Beat the 2 whole eggs and 3 egg whites together, then beat in about 1/2 cup of the flour and milk mixture. Then beat the egg mixture into the remaining flour and milk mixture.
In the saucepan you used for the milk, bring the cream almost to a boil.
Sprinkle the salt over the batter and slowly whisk in the warm cream.
Pull the hot popover pan out of the oven. I like to place the pan over the sink. Generously spray the cups of the popover pan with nonstick cooking spray and immediately pour the batter into the cups, filling each no more than 3/4 full. This 6-cup batch of filling should be exactly enough for 6 cups. Place the popover pan on the hot stone and bake for 9 minutes. Do NOT open the oven.
Turn down the heat to 425°F (218°C) and bake for 7 minutes more. Do NOT open the oven. Turn down the oven to 325°F (162°C) and leave the popovers in the oven for 20 to 25 minutes more, until risen and dry to the touch.
Gently run the popovers onto a wire rack to cool for a minute or so. Serve immediately with really good butter and preserves. (You can make these popovers several hours ahead and rewarm them at 300°F (149°C) for 5 minutes. Or, when they are completely cool, you can seal them in heavy resealable freezer bags and freeze. Reheat them in a 300°F (149°C) oven for about 5 minutes.)