Prepare a baking sheet by lining it with parchment paper. If you choose to make a template to follow, make for rows of four circles with a pencil. Flip the parchment paper over so the pencil doesn't get into the food.

Sift together the almond flour, PB2, and powdered sugar. If you can't find almond flour you can always make it with almonds and a food processor. Finely grind the almonds and sift through a fine mesh sifter. Discard or snack on any large pieces.

In a large mixing bowl, add in egg whites. Turn on high and beat until the egg whites form a soft peak meringue.

Add in the granulated sugar, salt, and cream of tartar. Mix on high until a stiff peak meringue forms.

Very lightly and carefully fold in a third of the almond flour mixture into the meringue with a spatula. All together you'll want to have about 45 turns. If you don't mix enough the macaron shell will be extremely fluffy and cracked. If you over mix, the macaron shell will be extremely flat and might not form a foot.

Repeat with the rest of the almond flour mixture.

Fill a piping bag with the macaron shell filling. I just used a coupler on the end of my piping bag. Pipe macaron shells on the baking sheet.

Let the macarons dry until they are no longer tacky to the touch. It will take 20 minutes to 1 hour. If you don't let them completely dry, they can also crack.

Place in the oven for about 18 minutes until they no longer stick to the parchment paper.

Let the macaron shells cool.

In a microwave bowl, add the heavy cream. Microwave for 1 minute and 45 seconds. Make sure you use a bowl that will provide plenty of room for the cream to rise as it gets hot. I used a 2 cup measuring cup to heat my cream in.

In a separate bowl, add the milk chocolate and peanut butter chips.

Pour the hot heavy cream into the bowl with the chocolate and peanut butter chips. Let it sit for about 1 minute. Whisk the cream and chips together. If there is still cream on the surface, keep whisking. It just needs to be mixed more. When it is completely incorporated, it will be thick and look like melted chocolate.

Cover the bowl with plastic wrap and place in the fridge for a 2-3 hours until it sets up. We want it at a consistency that can be piped.

Place the ganache filling in a piping back. It's going to be really thick, so I wouldn't bother with a fancy tip, just a coupler. Pipe a circle in the middle of the bottom macaron, and place the top shell on. Rock it back and forth, carefully not to crack the shell, to spread the filling to the outer edges.