Low-Calorie Spiced Pumpkin Muffins (Oat-Based)

Rolled Oats: $40 \text{ grams}$ . This quantity represents the controlled daily portion of permitted whole grains.
Fat-Free Natural Yogurt: $100 \text{ grams}$ . This is a core ingredient that is used freely to provide moisture and replace high-fat ingredients.
Pure Pumpkin Puree (Not Pie Filling): $50 \text{ grams}$ .
Small Egg: $1$ .
Baking Powder: $1 \text{ teaspoon}$ .
Vanilla Extract: $1 \text{ teaspoon}$ .
Pumpkin Pie Spice Mix: 1/2 $\frac{1}{2} \text{ teaspoon}$ Cinnamon, Nutmeg, Ginger.
Sugar Substitute (Sweetener): To taste. Use a zero-calorie sweetener.
Low-Calorie Cooking Spray: A small amount for greasing the tins.