Ripen the culture: Heat 1 gallon of whole milk over low heat until it reaches exactly 90°F. Turn off the burner. Sprinkle 1/8 tsp of mesophilic starter culture powder over the surface of the milk. Let it rehydrate for 2 minutes, then stir thoroughly using a gentle top-to-bottom motion. Cover with a lid and let it sit completely undisturbed on the counter for 1 hour
Add structural elements: After 1 hour, pour in the diluted calcium chloride mixture and stir for 30 seconds. Immediately follow with the diluted liquid rennet mixture. Stir using a gentle up-and-down, top-to-bottom motion for exactly 1 minute to distribute it evenly. Use the flat bottom of your spoon to completely still the liquid until it stops moving. Cover and let sit completely undisturbed for 1 hour
Cut the curds: Check for a "clean break" by inserting a knife at a slight angle and lifting. If the custard-like mass splits cleanly with sharp edges, it's ready. Slice the solid curd mass into a 1/2-inch square checkerboard grid, slicing vertically and horizontally all the way to the bottom of the pot. Angle your knife slightly on the final passes to create uniform cubes. Let the cut curds sit completely untouched for 10 minutes to "heal" and form a protective skin
Slow cook the curds: Turn the burner on to a very low setting. Because the pot sat off the heat for two hours, the temperature will have dropped to the high 70s or low 80s. Slowly raise the temperature of the pot up to 115°F over the course of 30 to 45 minutes. Every few minutes, take a slotted spoon and stir very gently from the bottom up to keep the cubes from fusing together. Turn off the heat once the curds shrink, firm up, and feel springy to a gentle squeeze.
Strain and shock: Pour the cooked curds and whey into a large colander lined with two layers of quality cheesecloth. Let the warm whey drain for 1 to 2 minutes. Gather the four corners of the cheesecloth into a loose pouch and plunge the entire bundle directly into a large bowl of ice-cold water. Gently swish it around for 30 seconds to lock in that plump, individual chunk structure and wash away surface whey.
Final drain & dress: Lift the pouch out, give it a very gentle squeeze, and let it drain in the colander for 15 minutes until all excess water is gone. Transfer the firm, plump curds to a bowl, add 1/2 tsp of sea salt, and fold in 6 to 8 tablespoons of cold heavy cream