Preheat oven to 200C. Pour milk into heavy, stainless steel pot and add calcium chloride if using pasteurised milk, stir well.
Using a thermometer, slowly heat milk to 13C if using chilled milk. Stirring constantly, add the citric acid mixture. Increase heat to 55C, constantly very slowly and being very careful not to cut the curd with your spoon. Once 55C is reached, remove from heat and stir in rennet mixture (using an up and down motion with your spoon so as not to break up the curd). Cover pot and leave to rest 15-30 minutes (until the curd has separated from the whey and the curd pulls away from the edge of the pot).
Prepare a sheet of baking paper large enough to wrap around the beetroot. Clean and trim baby beetroot and place in baking tray lined with baking paper. Drizzle over olive oil and season with salt and pepper. Wrap baking paper loosely around beetroot to form an airtight parcel and place in oven, cook 20-25 minutes until tender when pierced with a knife. When beetroot is cool enough to touch, gently scrape peel using a sharp knife and cut into quarters.
Now cut the curd. Take a long knife and cut the curd in a checkerboard pattern from top to bottom and side to side, cutting lines about 4 cm apart.
Return curds to heat and warm over low heat to reach between 43C-50C. Remove from heat and gently stir for 2-5 minutes. This allows curd to firm a little. The longer you stir, the firmer the cheese skin.
Pour or ladle curds into strainer to separate from whey. (Keep whey to make a fresh batch of ricotta another time, or discard). Transfer ¼ of well-drained curds into a bowl and break up with fingers. Add cream and a pinch salt to form a thick, wet filling like a very soft ricotta.
Heat 2 litres water in saucepan or kettle and keep water at about 85C, ready to heat curds as needed. Pour half the water in a medium bowl that fits the colander inside it, and stir in a large pinch salt. Dip colander of curds into the hot water bath, let sit 2 minutes, or until they become gooey and stretchable. Work in very hot water (wear gloves if liked), adding more hot water as needed to keep curds hot.
Prepare an icewater bath in a medium bowl, set aside. Mould curds into 3 or 4 balls, and keep squeezing balls and gently stretch them out for 5 minutes, massaging them well. Stretch the curds until smooth and glossy. Shape one ball into a flat disk like a small pizza dough on the bench, working quickly while it’s still hot (dip back in very hot water to improve elasticity). Dollop a large spoonful of the cream mixture and roll and pinch in sides to form a pouch. Transfer ball into an ice water bath and repeat with remaining balls.
Serve with roasted baby beetroot and thick slices of sourdough toast, drizzled with extra virgin olive oil and seasoned with sea salt and freshly ground black pepper.