For the Whoopie Pies

1. Line two large baking pans with parchment paper, or use non-stick pans.
2. With a sifter or fine mesh sieve, sift together the flour, baking soda, and salt into a large bowl or onto a large piece of parchment paper. 
3. In a medium saucepan over low heat, melt together the butter, chocolate chips or chopped chocolate, and brown sugar. Set it off the heat to cool slightly.
4. In a large bowl or the bowl of a stand mixer fitted with a paddle attachment, beat the eggs with the vanilla extract at medium speed until combined.
5. Beat in the chocolate mixture on low speed, scraping the bowl and beater as you mix. In several additions still on low speed, beat in the dry ingredients. The batter will be very thick. 
6. Chill the batter for one to two hours, or cover and chill it overnight. If you chill it overnight, let the batter sit at room temperature for 30 minutes to soften (it will make scooping easier).
7. Preheat your oven to 325° F.
8. With a one to two-inch ice cream scoop with a release (or two large spoons and your hands), scoop the batter into balls. Rinse the scoop in a cup of hot water to keep it clean and prevent the batter from sticking to it.
9. Space the scooped dough two inches apart on a couple of parchment-lined or non-stick baking pans.  Aim for an even number of batter mounds. Flatten each one about halfway down with a wet palm. Or you can also lay a second piece of parchment on top of the pan and flatten the balls all at once using the bottom of the second pan.
10. Bake the whoopie pies for 10 to 14 minutes for two-inch pies, just until they begin to rise and lose their sheen. Cool the pie halves for a few minutes on the pan until you can handle them. Then cool them completely on a rack or plate before filling. Warm pies will melt the fillings. 
11. Scoop or pipe your filling onto half of the baked whoopie pie halves. Then top with the remaining ones.
12. Store the pies chilled, but serve them at room temperature for the fullest flavor and best texture.

Cream Cheese Filling

1. Sift the powdered sugar with a fine mesh sieve or a sifter to remove any lumps. 
2. With a hand mixer (or stand mixer with a paddle), beat the softened cream cheese on medium-low speed until smooth.
3. Slowly beat in the powdered sugar in several additions.
4. Beat in your seasonal flavoring, if using, and then the vanilla extract, heavy cream, and salt. 
5. Store any leftovers in the refrigerator for up to a week. But fill the pies with it and serve it at room temperature.

Homemade Marshmallow Creme

1. Place the egg whites in a heat-proof bowl near the stove and plug in your hand mixer nearby. Or place them in a stand mixer fitted with the whisk attachment.
2. In a small saucepan, combine the sugar and water. Place a candy thermometer in the bowl if you have one, or have ready a digital kitchen thermometer. Bring the sugar and water to a boil, and boil until it reaches 235° F. This will take between three to six minutes, and depend entirely on your stove burner's intensity.
3. While the syrup comes up to the target temperature, beat the egg whites to soft peaks. Soft peaks are when the whites form floppy peaks off the tip of the beater when you pull it away. Beat in the lemon juice or cream of tartar once peaks begin to form. If your whites are whipped before the syrup is ready, just turn a stand mixer on low speed or your hand mixer off. 
4. As the sugar syrup in the pot approaches 235° F, turn the mixer back on low speed. Once the syrup hits 235° F, slowly drizzle the hot syrup into egg whites while continuing to beat. Do your best to aim for the side of the bowl and avoid hitting the beater (this will splatter hot syrup all over the bowl and leave chunks of hard sugar in your filling).
5. Once all of the syrup is beaten in, speed the mixer up to medium-high, and beat until the meringue cools down to room temperature. 
6. Beat in a few granules of salt, and the vanilla bean seeds or vanilla extract. 
7. Use the meringue immediately, or store it refrigerated for a couple of days. Italian meringue is best enjoyed within a day or two. If any extra is stored chilled, it will need to be whipped again on high speed for a couple of minutes to revive it.