Miniature Jalapeño Souffles

INGREDIENTS

• 1 1/2 tablespoons pine nuts, very finely chopped
• 1/2 teaspoon Dijon mustard
• 1 tablespoon unsalted butter plus additional for buttering muffin cups
• 1 large egg, separated
• 1/4 teaspoon kosher salt
• 1/8 teaspoon black pepper
• 6 tablespoons whole milk
• 1 oz finely shredded Gruyère (1/4 cup)
• 1 small whole pickled jalapeño or 5 slices, seeded and finely chopped (1 tablespoon)
• 2 1/2 tablespoons all-purpose flour