Put the cashews and pecans into a food processor and blend until the mixture turns into a smooth nut butter, stopping occasionally to scrape down the sides of the bowl. This process can take between 5 to 10 minutes, so be patient. Next, add the sugars, butter, and vanilla extract. At first, the sweeteners will thicken the nut butter considerably, but keep processing—the heat generated will eventually melt the sugar and help smooth out the nut butter. If it still feels too thick, continue blending!

Here comes the tricky part: once your nut butter is fully processed, you need to chill it in the fridge. If you skip this step, the chocolate chips will melt into the nut butter and turn the whole mixture brown (trust me, it happens!). After chilling for about 25 minutes, fold in the mini chocolate chips. This will yield approximately 1 1/2 cups of nut butter—more than enough to fill all 24 chocolate cups. Any leftover nut butter can be stored in the fridge for 2 to 3 weeks and makes a great spread for crackers or toast.

While the "cookie dough" chills, line a mini muffin tin with 24 paper liners. Melt 1 1/4 cups of chocolate chips—microwaving works well by heating on full power for 20 seconds, stirring, then heating for another 30 seconds and stirring until smooth. Spoon about 1/2 to 1 teaspoon of melted chocolate into each liner, then use a pastry brush to coat the sides with chocolate. Freeze the pan for 20 minutes. By this time, the nut butter should be nicely chilled.

Take the muffin tin and nut butter out of the fridge, then spoon 1 teaspoon of the nut butter into each chocolate cup. Return the pan to the freezer while you melt the remaining chocolate chips. Once melted, spread the chocolate over the top of each cookie dough cup, smoothing it with a spoon. Freeze again for 15 to 20 minutes. These treats can be left out at room temperature for a few hours (they might soften a little), but they taste best when stored in the fridge.