PB&J Cinnamon Buns with Marshmallow Cream Cheese Frosting (for Dan Levy)

1. For the dough: In a small saucepan, bring the milk to a boil. The moment it reaches a boil, remove from the heat. (This process is called scalding, and it ensures the milk doesn't affect the yeast's ability to rise. Don't skip it!)
2. Pour the hot milk into the bowl of a stand mixer and add the butter. Stir, allowing the butter to melt completely, then add the granulated sugar. Wait until the mixture is just warmer than room temperature, then stir in the yeast. Allow the yeast to sit for 10 to 20 minutes to activate and get bubbly and frothy. (If the yeast does not bubble up after 30 minutes, start again with fresh ingredients, as the yeast may be dead.)
3. Attach the dough hook to the mixer and turn the mixer to low. Add the whole eggs, egg yolk, 4 cups of the flour, the salt, and vanilla. Beat the dough until it pulls away from the sides. Run the mixer for about 10 minutes to allow the dough to stretch and develop the gluten. If the dough seems too sticky after the first 2 to 3 minutes, add an additional 1/4 cup flour. After mixing for 10 minutes, turn the mixer off. Cover the top of the bowl with plastic wrap or a kitchen towel and allow the dough to rise until doubled in size, about 1 1/2 hours in a warm kitchen.
4. For the filling: In a stand mixer fitted with the paddle (or in a bowl with a wooden spoon), cream the brown sugar and butter together until light and fluffy. Add the cornstarch and cinnamon and beat until smooth. Gradually add the strawberry preserves to make a smooth filling.
5. Dump the dough onto a lightly floured surface. Press it flat with your hands and fold into thirds. Press flat again, turn, and fold into thirds again. Roll the dough out into a 16-by-20-inch rectangle.
6. Use a large offset spatula to spread the filling over the dough in a thin layer. Leave 1 inch of dough bare on one of the long edges of the rectangle. Sprinkle the peanut butter chips evenly all over the filling. Starting with the filling-covered long edge of the dough, roll the dough tightly but gently (this filling can get a bit messy, don't fret) toward the uncovered edge to form a tight log. Carefully place the log onto a tray and place it in the freezer for 10 minutes to make it a bit easier to cut.
7. Line a 9-by-13-inch glass baking dish with parchment paper. With a sharp knife, cut the log crosswise into 9 equal rolls. Tuck the loose end of each roll underneath the roll to secure it so it doesn't unravel in the oven and place the rolls in the baking dish. Cover the dish lightly with plastic wrap and a kitchen towel and let the buns proof for about another 45 minutes, or until puffed up slightly.
8. Preheat the oven to 375 degrees F (or 350 degrees F on the convection setting).
9. Bake for 22 to 25 minutes, until the edges are golden and the centers of the rolls start to puff up. (You can also take the internal temperature of the buns, which should be at 195 degrees F when done.)
10. For the frosting: Meanwhile, in a stand mixer fitted with the paddle (or in a bowl using a hand mixer), beat together the cream cheese, butter, vanilla, salt, and powdered sugar until smooth and creamy. Finally, fold in the marshmallow cream until just combined.
11. The moment the rolls come out of the oven, gently spread three-quarters of the frosting over the tops and allow it to melt and seep into the cracks and layers. Wait 5 to 10 minutes and then add more frosting if desired.
12. To garnish (if desired): Top with a drizzle of warmed peanut butter and jam, and a sprinkle of chopped roasted peanuts or crumbled freeze-dried strawberries. For a little extra pizzazz, top each bun with a dollop of extra marshmallow cream and toast it using a kitchen torch!
13. Store airtight in the refrigerator for up to 3 days. To reheat, microwave on a plate for about 30 seconds, or until warm and softened.

Marshmallow Cream:

1. Pour the egg whites into a heatproof bowl and set the bowl over a pot of simmering water (the water should not be touching the bottom of the bowl). Whisk vigorously and stream the granulated sugar and cream of tartar into the egg whites. Keep whisking over the double boiler until the egg whites thin out, become whitish in color, and there are no more noticeable granules of sugar when you rub some of the mixture between your fingers.
2. Remove from the heat and pour the mixture into the bowl of a stand mixer fitted with the whisk (or into a bowl and using a hand mixer or whisk). Add the vanilla, coconut extract (if using), and salt and whisk on high until stiff peaks form. This will take about 5 minutes.
3. Store in a sealed container or bowl in the fridge until you are ready to use. It will keep for about 7 days in the fridge.
4. Use on peanut butter sandwiches, layer it with Nutella in a dish and dip graham crackers in it for a gooey s'mores dip, add it to raspberry jam on a toasted English muffin, or put a big dollop on a mug of hot cocoa (you can even torch it to get the toasted marshmallow effect).