In a large bowl with a hand mixer or in the bowl of a stand mixer fitted with a paddle attachment, beat 3/4 cup of butter and 1/2 cup of cream cheese on medium speed until smooth.
Next, add 1 1/2 cups granulated sugar and mix on a medium-high speed for a couple of minutes, until the mixture becomes lighter in color.
Add in 1 egg, 2 tsp almond extract (optional), and 2 tsp vanilla bean paste or vanilla extract. Mix on a medium speed until incorporated.
In a separate bowl, whisk together 3 cups flour (use a scale or fluff the flour in the bag, then spoon it into the measuring cup and level it), 1 Tbsp cornstarch, 1 tsp fine salt, and 1/2 tsp baking powder.
Mix the dry ingredients into the butter mixture on a low speed until they are JUST incorporated. Scrape the sides of the bowl with a rubber spatula as needed.
At this point, the dough should still be pretty thick and sticky. Divide the dough in half and wrap each portion of dough in a piece of plastic wrap. I like to flatten the dough out into a rectangle that's about 1/2 inch thick to make it easier to roll out once it's chilled.
Chill the dough in the fridge for about 1 hour or in the freezer for 30 minutes. It can also be chilled overnight. Preheat the oven to 350°F / 175°C for about 30 minutes before you plan to roll out the dough, and line two large baking sheets with parchment paper (the cookies will spread more if you bake them on a silicone mat). Set aside.
Take one piece of dough out of the fridge, leaving the other in there to continue to chill. If you put the cookie dough in the freezer, let it sit at room temperature for 5-10 minutes to soften up a bit before trying to roll it out. Unwrap the cookie dough and lay the plastic wrap out flat on your counter. We will be rolling out the cookie dough on the plastic wrap to make cleanup a breeze and make cutting out the cookies easier. Dust the top of the cookie dough with flour.
Roll the chilled dough to be 1/3 inch thick (these rolling pin rings help a ton with getting a consistent thickness) and use a 2- or 3-inch skull-shaped cookie cutter to cut out as many cookies as you can. The cookies don't spread much as they bake, so you can place them about 1 inch apart. If desired, press the tops of the cookies into white sanding sugar.
Chill the cut-out cookies one more time in the fridge for 15 minutes or the freezer for 5 minutes to help them keep their shape as they bake.
Bake one sheet of cookies at a time for about 14-16 minutes on the middle rack of your oven (bake time can vary based on the cookies' size and the dough's thickness). Keep a close eye on the cookies and be sure to pull them out before the edges start to brown.
Let the baked cookies cool on the pan for about 15 minutes, then transfer to a wire rack to finish cooling. You can dust them with powdered sugar if you want them to be a brighter white color or to add a little sweetness.
While the first batch bakes and cools, knead together the cookie dough scraps and rewrap them in plastic wrap. Pop them back in the fridge to chill.
Pull out the second chilled portion of dough and repeat the steps above. Then repeat with the chilled dough scraps.