Special equipment: A candy thermometer and a piping bag with a 1/4-inch round tip
For the pistachio cream filling: Preheat the oven to 300 degrees F.
Spread the pistachios onto a baking sheet and toast for 15 minutes. Let cool.
Place the granulated sugar and 1 tablespoon water in a saucepan and bring to a boil over medium heat (brush down the sides with water to avoid any clinging granules of sugar and prevent crystallization). Cook the syrup until it reaches 250 degrees F on a candy thermometer. Add the toasted pistachios to the hot syrup and stir until the nuts are well coated. When all the sugar coats the pistachios and any remaining syrup turns powdery white, pour the nuts onto a baking sheet to cool.
Once cooled, place the pistachios in the bowl of a food processor with the almond flour. Blend until the nuts resemble a coarse meal, approximately 1 minute. Slowly drizzle in the oil while continuing to blend the mixture. Add the butter, almond paste, almond extract and 3 tablespoons water. Keep mixing until mixture is a smooth paste, approximately 3 minutes.
For the macarons: Mix the powdered sugar, almond flour and salt in a bowl using a whisk; set aside. In a separate bowl using a hand mixer, mix the granulated sugar, vanilla, food coloring and egg whites. Whip until the batter has firm shiny peaks. Take one-third of the wet mixture and fold into the dry ingredients. Gradually fold in the remaining batter. Once the dry ingredients have been absorbed, run a rubber spatula over the mixture to create a shine. This process is called macaroning and is key to the overall recipe.
Line 2 cookie sheets with parchment paper. Transfer the batter to a piping bag with a 1/4-inch round tip. Pipe the mixture in 1-inch rounds onto the cookie sheets. It's important to create a consistent size for each cookie. Let stand for 30 minutes to create a thin crust on the outside.
Adjust the oven racks: Put one in the lower third of the oven and a second in the upper third of the oven. Preheat the oven to 300 degrees F. Bake until the macarons puff and rise to form ''feet'' and are crisp, 17 to 20 minutes. Let cool completely on the cookie sheets before filling.
Put about 1 teaspoon of pistachio cream filling between 2 cookies to create the finished macarons.
Almond paste can be purchased in the baking aisle of most grocery stores.