Crumble-Topped Zucchini Muffins

Ingredients

• 1/4 cup whole wheat pastry flour
• 3 tablespoons date sugar
• 3 tablespoons unsalted butter, melted and cooled
• 2 tablespoons rolled oats
• 1/4 teaspoon ground cinnamon
• 1/8 teaspoon grated nutmeg
• pinch fine sea salt
• 1 cup whole wheat pastry flour
• 1/2 teaspoon baking powder
• 1/4 teaspoon baking soda
• 1/8 teaspoon freshly grated nutmeg
• 1/2 cup plus 1 tablespoon date sugar
• 1/3 cup olive oil
• 2 tablespoons milk
• 1 large egg
• 1 teaspoon vanilla extract
• 1 heaping packed cup finely shredded zucchini
• 1/2 cup chopped, toasted walnuts (optional)