Step 2: Mix the Gravy and Broth
In a large bowl or measuring cup, whisk together the entire can of sausage gravy and the two cups of chicken broth until well combined. The mixture will look thin — considerably thinner than the gravy from the can — and this is exactly right. The liquid needs to be loose enough to fully surround and submerge the dry noodles during baking. As the noodles cook, they will absorb a significant portion of the liquid and release starch that thickens the remaining sauce back to a proper gravy consistency. If the finished sauce looks too thick for your taste when the casserole comes out of the oven, stir in a small splash of warm broth or water before serving to loosen it slightly.
Step 3: Assemble the Casserole
Spread the uncooked egg noodles in an even layer in the prepared baking dish. Pour the gravy-broth mixture evenly over the noodles, making sure every noodle is submerged or at least thoroughly coated with liquid. Use the back of a spoon to gently press any noodles that are sitting above the liquid surface down into the sauce. Every noodle needs contact with the liquid in order to cook through properly during baking — noodles that sit dry on top of the liquid may remain crunchy in the center even after the surrounding noodles are fully cooked.
