Cheesy Savory Butternut Squash Muffins

INGREDIENTS

• 4 teaspoons baking powder
• 3/4 cups whole milk
• a sprinkling of salt and pepper
• 2 teaspoons German-style mustard
• freshly ground black pepper
• 1 medium butternut squash, peeled, seeded, and cut into 1/2 inch cubes
• 2 tablespoons olive oil
• 1/4 teaspoon ground nutmeg (optional)
• 3/4 crumbled (in large crumbles) feta cheese
• 2 cups all purpose flour
• 2 eggs
• 3/4 cups freshly grated Parmesan cheese
• 2 small handfuls of spinach, well chopped
• 1 teaspoon salt