Preheat oven to 350°F. Cut off top third of each squash, and scoop out pulp, using a serrated corer or melon baller, leaving a 1-inch shell intact. Coarsely chop pulp; reserve 1 cup of chopped pulp, and discard remaining pulp. Place squash bowls in an 11- x 13-inch baking dish, and sprinkle with salt. Bake in preheated oven 10 minutes.

Place bacon in a large nonstick skillet over medium-high, and cook, stirring occasionally, until starting to brown, about 5 minutes. Add beef to skillet, and cook, stirring to crumble, until starting to brown, about 6 minutes. Add onion, garlic, and reserved 1 cup chopped squash pulp to skillet, and cook, stirring occasionally, until tender, about 3 minutes. Stir in spinach; cover and cook until spinach is wilted, about 2 minutes. Uncover and cook until liquid is almost evaporated, about 1 minute. Transfer beef mixture to a medium bowl; cool 10 minutes.

Stir eggs, cooked rice, pepper, and 3 tablespoons of the dill into beef mixture. Gently stir in cheese. Spoon mixture into baked squash bowls.

Bake squash in preheated oven until tops begin to brown and squash is tender, about 30 minutes. Sprinkle squash with remaining 1 tablespoon dill.