In a large skillet, heat 2 tablespoons butter over high heat until the butter foams and subsides. Add the bread, working in batches if necessary, and fry over high heat until golden and crispy. Rub each bread slice with the cut side of 1/2 a garlic clove, cut into very small pieces, and set aside.
In a medium stockpot, heat the remaining butter over medium-high heat. Add the squash, salt and pepper, to taste, cinnamon and lemon juice and cook over medium-high heat for 20 to 25 minutes, until the squash is very soft and broken down. Add the bread crumbs and milk and bring to a boil. Lower heat and cook over medium-low for 15 minutes, adjust the seasoning and serve immediately over bread pieces.