Heat the oven. Preheat oven to 350°F
Prepare the bread. Slice and cube up your day-old bread and place into a large bowl.
Make the eggnog batter. Mix eggs, eggnog, cinnamon, and nutmeg together in a bowl.
Coat the bread cubes. Pour the eggnog mixture over the bread cubes and stir until all of the cubes are evenly coated.
Chill. Cover and refrigerate for 1 hour, up to 3 hours.
Make the streusel. Combine the sugar, flour, cinnamon, and nutmeg in a medium bowl. Cut in the butter with a pastry cutter or two 2 forks. You can also add the streusel ingredients to a food processor and pulse until the mixture is crumbly.
Assemble. Divide the bread mixture evenly between lined or greased muffin cups. Spoon the streusel mixture over the muffins.
Bake. Bake the muffins for 35-40 minutes, until the tops begin to turn golden brown.
Serve. Serve with maple syrup, and if desired, a bit of creme fraiche.