Bring a small pot of water to a rolling boil, then turn off the heat and blanch the pistachios for 1-2 minutes. Immediately after, place them into an ice bath. *You can skip these first two steps if you do not care about color, or if you plan to use food coloring. The reason I blanch them first is because they turn a little brighter green, and it helps to loosen the brown skins for removal. This way I can get a nice bright green color naturally.
Using a dish towel, rub the pistachios to loosen the brown skins. After rubbing vigorously for a few seconds, the skins should be relatively easy to peel off.
Blend the pistachios in a food processor until it turns into a clumpy paste, like the picture below. You may need to scrape down the sides a couple of times.
Next add a couple tablespoons of milk, and continue processing until it turns into a smooth paste, scraping down the sides as needed.
Combine the milk, crema, sweetened condensed milk, almond extract, and cellulose gum with an electric mixer. The cellulose gum works as a stabilizer and gives you a paleta that is creamy, not icy. This mixture is not meant to thicken too much after mixing, so don't worry if it looks a little too runny to you.Alternatively: This is what I recommend if you're using cornstarch. Combine the milk, crema, salt, and sweetened condensed milk in a small sauce pan. When combined, turn on the heat to low. Stir and do not let it boil, but once it's steaming add about 1/4 cup to a small bowl with 2 tsp cornstarch and mix until smooth. Then add it back to the saucepan and continue cooking over low heat, stirring until it thickens. Then let it cool before continuing to the next step.
Add the pistachio paste and mix until combined. It is much easier to use an immersion blender to fully incorporate the pistachio paste.
Optional: if you like pistachio chunks in your ice cream, you can fold them in now. I recommend crushing about 1/2 cup of pistachios.
Pour into your popsicle mold, leaving a tiny bit of space at the top to allow it to expand. It depends on your popsicle mold, but be mindful about the popsicle stick placement when you're sticking them into the mold. You don't want to push them all the way down because it leaves very little room to hold the stick, but you also want to make sure its deep enough to pull them out completely.
Freeze for at least 8 hours. To remove the paletas from the mold, place it in warm water for about 20 seconds to loosen. With a little wiggling and force, the popsicles will slide out perfectly.