2 1/2 sticks (1 1/4 cups) unsalted butter, melted and cooled
1 tall can evaporated milk + enough water to measure 2 cups
1 (16 oz) container regular sour cream (not light)
4 large eggs
2 large egg yolks
2 teaspoons vanilla
3 cups white sugar
7 cups all purpose flour
4 1/2 teaspoons baking soda
1 teaspoon iodized salt
1 package frozen raspberries (no need to thaw) or 2 cups fresh raspberries
1 package semi sweet chocolate chips (measure 1 cup semi chocolate chips and melt in microwave for swirl effect)
Preheat the oven to 350 degrees F.
Line standard or jumbo muffin pans with paper liners.
In a medium mixing bowl, aerate to blend together with a whisk: flour, baking soda, and salt.
In a large mixing bowl, beat (with whisk or electric mixer) liquid ingredients together to combine well: melted butter, milk, sour cream, eggs, egg yolks and vanilla.
Add the dry ingredients to the wet and stir just to combine (the batter will still be somewhat lumpy and few streaks of flour will be visible; do not overmix.).
Gently fold in the fresh or frozen raspberries and unmelted chocolate chips.
Spoon melted chocolate chips on top of batter and slowly swirl through batter several times to create marble effect.
Spoon into the prepared muffin pans.
Optional: Sprinkle granulated sugar over the muffins and bake until they are golden brown and spring back lightly when pressed in the middle, about 30 to 40 minutes.
Let cool in the pans for 10 minutes, then remove and cool on wire racks.