Mix citric acid in water and stir until dissolved.
In a heavy-bottomed pot, heat milk to 140℉, stirring on occasion. Turn off heat when you reach 140℉.
Line colander with sterilized butter muslin, place colander into a draining container.
Prepare a cheesemold or small container for finishing cheese. Grease with butter, making sure to grease the corners and sides well.
Add citric acid solution to heated milk, and stir in gently. Allow to sit for 5 minutes.
Using the butter muslin setup, drain off whey.
Once drained, grab the opposite corner of the butter muslin, rolling the cheese in the colander to drain off excess whey. Repeat using the additional opposite corners. Cheese will form a soft ball.
Melt butter in the same heavy-bottomed pot.
Transfer the cheese back to the heavy-bottomed pot.
Add baking soda and salt. If using cheddar cheese powder, add now. Begin mixing.
Melt cheese on medium heat until completely melted, stirring constantly. Cheese may puff up, keep stirring until completely melted.
Once melted, pour cheese into prepared mold and chill.
Once chilled, remove from mold and enjoy.