Add buttermilk, sugar, cocoa powder, salt, and vanilla into a blender. Pulse a few times to combine the ingredients, then blend on medium speed for 1 minute. Scrape down the sides.
Add egg yolks and heavy cream and blend on low speed for 15 seconds until ingredients are well combined, scraping the sides again if needed.
Add 1/2 teaspoon of food coloring and pulse until well incorporated. Add more food coloring if a darker red color is desired.
Divide batter evenly into 6 – 6 ounce ramekins. Place a coffee filter on top of the ramekins and trim so it just barely hangs over the sides. Then cover the coffee filter with a piece of foil just large enough to cover the filter.
Add 1 cup of water to the pressure cooker pot and place a trivet inside. Place 3 ramekins on the trivet, top with another trivet, follow with 3 more ramekins. You can also carefully stack the top three ramekins on top of the bottom ones if you do not have a trivet that will work for this.
Secure the lid and turn pressure release knob to a sealed position. Cook at high pressure for 8 minutes.
When cooking is complete, use a natural release for 10 minutes and then release any remaining pressure.
Place ramekins on a cooling rack and remove foil and coffee filters (you can reserve the foil for covering the ramekins and storing them in the refrigerator later). Cool on wire rack until room temperature, about 2 hours, then cover and chill in the refrigerator for at least 4 hours or up to 3 days.
To serve, uncover the ramekins. If there is any moisture on the custard, dab it off with a paper towel. Sprinkle 1 teaspoon of turbinado sugar on top and tilt for even coverage.
To caramelize the sugar, hold kitchen torch 3-4 inches from custard and move flame continuously over the sugar until is golden brown (this can also be done under the oven broiler. Watch closely! It will brown quickly). Serve immediately.