Preheat the oven to 425°Fahrenheit/218°Celsius and adjust the rack to be in the middle of the oven. Place 12 liners in 2 muffin pans, leaving every other muffin cavity empty.
In a small or medium bowl, whisk the flour with the salt, baking soda, baking powder, ground nutmeg, and ground cinnamon. Set aside.
Place the butter in a microwave-safe bowl and microwave until ocmpletely melted.
½ cup unsalted butter
Pour both sugars into the cooled melted butter and whisk together.
½ cup light brown sugar, ½ cup granulated sugar
Whisk in the eggs, mashed bananas, sour cream, and vanilla extract.
1 ½ cups mashed bananas, 2 large eggs, ⅓ cup sour cream, 1 teaspoon vanilla extract
Pour the dry ingredients in and use a rubber spatula to fold together until just combined.
Stir in the raspberries and white chocolate chips. I like to keep a few raspberries to the side to add on top later!
½ cup white chocolate chips, 1 cup raspberries
Pour the banana muffin batter into your prepared liners to the top then sprinkle over the extra raspberries.
Bake in the preheated oven for 5 minutes, then lower the temperature (without opening the door) to 350/175 and bake for an extra 14-16 minutes. Let the muffins cool in the pan for 10 minutes before removing to a wire cooling rack to cool completely.
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. I have provided a conversion to US cups but please note that I haven't tested the recipe with this method. I make sure that all of my ingredients are at room temperature before I start the recipe, so pull out all of the ingredients about an hour or two before you start baking. Salt: If you don't have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt. I'm using Diamond Crystal Kosher Salt and not Morton Salt which is too salty for this! Sour Cream: if you don't have sour cream, use full-fat yogurt or Greek yogurt. Chocolate Chips : feel free to use semi-sweet chocolate, milk chocolate, or dark chocolate chips. Raspberries: you can use fresh or frozen raspberries. If using frozen, you don't need to defrost them beforehand. Storage: keep in an airtight container at room temperature for 2 days, or in the fridge for five days. Freezing: freeze baked and cooled muffins in a freezer bag. Let them thaw in the fridge or at room temperature.