gougères + stuffed mushrooms

INGREDIENTS

• 1 cup milk
• 4 tablespoons unsalted butter (1/2 stick)
• 1/4 teaspoon salt
• Dash cayenne pepper
• 1 cup all-purpose flour
• 3 large eggs
• 1/2 teaspoon paprika
• 1/2 cup grated Parmesan cheese
• 1 1/2 cups grated Swiss cheese (Emmenthaler or Gruyere)
• Coarse salt (fleur de sel or kosher salt) to sprinkle on top
• 8 ounces bacon slices
• 1 cup chopped onion
• 1 10-ounce package chopped frozen spinach, thawed, squeezed dry
• 4 ounces feta cheese, crumbled (about 3/4 cup)
• 4 ounces cream cheese, room temperature
• 1/4 teaspoon dried crushed red pepper
• 2 3/4 pounds button mushrooms (about 48; each about 1 1/2 inches in diameter), stemmed