Add most of the diced bacon (save some for garnish) and mayonnaise and mix well to combine. Once fully combined, scoop about 2 tsp. of egg yolk mixture back into the eggs.
Preheat your oven to 375 degrees F. Lightly spray a large baking dish with nonstick cooking spray. Remove and discard giblets, then rinse and dry the hens inside and out with a paper towel. Salt and pepper hens to taste and set aside.
Put in the oven, and bake for about 11/2 hours (larger batches will take longer). Every 20 minutes or so, open the oven, and, with the back of a large spoon, break the crust the cream will form, and turn over any of the top sausage pieces that may be beginning to brown. For the final 20-30 minutes, leave everything untouched to form a golden top. Cream should be nearly all broken down and absorbed with just a bit of creamy, buttery-ness between the potato slices.