Add water and baking soda to a large pot. Heat on high to boil.
Line a baking sheet with parchment paper and preheat oven to 375F.
Cut the crescent sheet into 8 equal pieces.
Roll each sausage link in the crescent sheet pieces or into a crescent roll (sausage can stay frozen).
Once the water is boiling, add 1 sausage roll at a time into the water for 20-30 seconds. Remove and place on baking sheet. Sprinkle with kosher salt and repeat with remaining sausage rolls.
Bake for 17-19 minutes until lightly browned.
While baking, make the cheese sauce.
Heat a medium sauce pan over medium-low heat. Add butter and flour and whisk together until it forms a rue and thickens. Add in mustard and whisk again.
Slowly pour in whole milk. Whisk until thickened, about 2-3 minutes. Remove from heat.
Whisk in shredded cheese, whisk until completely melted.