These Toasty Walnut Muffins are a delightful, quick-to-make breakfast or snack option that combines the earthy crunch of toasted walnuts with the chewiness of oats and raisins. The batter is enriched with a beaten egg yolk and milk, creating a tender crumb that is moist yet satisfyingly hearty. A sprinkle of brown sugar and butter on top adds a caramelized sweetness that complements the subtle spice of cinnamon. Perfect for a busy morning, these muffins can be prepared in minutes using a microwave, making them an ideal choice for when you need a warm, comforting treat without the wait of traditional baking.