Ingredients

• 1 (.25 ounce) package active dry yeast
• 1 pinch white sugar
• ½ cup warm water
• 1 egg, at room temperature
• 3 tablespoons butter, at room temperature
• 2 ½ cups all-purpose flour
• 1 teaspoon salt
• 2 teaspoons lemon zest
• ½ teaspoon vegetable oil
• ½ red onion, sliced
• 1 cup shredded Gouda cheese
• ½ cup grated Parmesan cheese
• 2 jarred roasted piquillo peppers, diced
• ¼ teaspoon ground black pepper to taste
• 2 eggs
• 1 ½ cups heavy cream
• ¼ teaspoon stone-ground mustard