Ingredients

• 1/2 oz dried porcini mushrooms
• 2 1/2 cups all-purpose flour
• 1 1/2 tsp salt
• 6 large eggs, lightly beaten
• 2 1/2 cups whole milk
• 1/2 stick unsalted butter (2 Tbsp melted and 2 Tbsp cold) plus additional for popover cups
• 2 nonstick popover pans with 6 (2/3-cup) cups

Instructions

1. Grind porcini to a powder in an electric coffee/spice grinder or a blender (you’ll have about 1/4 cup). Whisk together porcini powder, flour, salt, eggs, milk , and melted butter until smooth, then let rest, chilled, 1 hour.
2. Preheat oven to 400°F with rack in middle. Butter popover cups. Cut remaining 2 Tbsp butter into 12 pieces.
3. Heat popover pans in oven 2 minutes. Remove from oven and add a piece of butter to each cup. Return to oven and heat until butter is bubbling, about 1 minute. Divide batter among cups (a scant 1/2 cup each) and bake until puffed and golden-brown, 30 to 35 minutes.
4. Pierce top of each popover with a sharp knife to release steam, then continue to bake until deep golden-brown, 5 to 10 minutes more. Serve immediately.
5. Popovers can be baked 4 hours ahead. Remove from pans and reheat on a baking sheet in a 350°F oven until hot and crisp.