In a saucepan, combine pumpkin, brown sugar, and pumpkin pie spice. Place over medium heat and bring to a simmer. Cook for 5 minutes, stirring constantly.

Add the heavy cream and stir to combine. Bring the pumpkin mixture back to a bare simmer, stirring constantly.

Place the white chocolate in a bowl or tall container. Pour the hot pumpkin mixture over the chocolate and let it sit for about a minute. Then use an immersion blender to combine until smooth. Stir in the corn syrup.

Pour the ganache into a bowl and press cling wrap onto the surface. Cool to room temperature. If not using the same day, cover and place in the fridge. Allow the ganache to come to room temperature before using.

Prepare 2 baking sheets with silicone mats, teflon, or templates and parchment paper. Fit a piping bag with a round piping tip. Set aside. Preheat oven to 290°F.

Pulse the powdered sugar, almond flour, and pumpkin pie spice in a food processor and sift into a bowl. Discard any large chunks. Whisk the dry ingredients and set aside.

Combine egg whites and powdered color.

In a clean stand mixer bowl, combine the sugar and the egg whites. Whisk to combine and place the bowl over a double boiler. Heat, whisking regularly, until the sugar dissolves, about 90 seconds. Remove the bowl from the double boiler and dry off the bottom.

Place the bowl in the stand mixer and whisk on medium speed until you have stiff peaks, about 10-15 minutes.

Add the dry ingredients to the bowl and begin folding the ingredients together. Continue folding until the batter flows slowly like lava.

Pipe macaron shells onto prepared baking sheets. Let the macarons dry until you can lightly brush the tops with your finger (about 30 minutes). Bake for 22-24 minutes, rotating halfway through. Gently poke shells; if firm, remove from the oven. If they wiggle, bake for another minute or two.

Let the macaron shells cool on the sheet for 10 minutes before transferring them to a cooling rack.

Pair up the macaron shells. Fill a piping bag with ganache and pipe a dollop onto one shell, then top with the other shell. Repeat with the remaining shells.

Place in an airtight container in the fridge overnight to let them mature. Remove 30 minutes before serving.