Preheat oven to 400ºF (200ºC).
In a large skillet cook bacon over medium heat and start rendering fat. Add onion and increase heat to medium-high, stirring frequently about 8 minutes, until onions start to brown and bacon crisps. Add potatoes and stir to coat well. Cook, stirring for about 5 minutes or until starting to brown.
Add wine and simmer for 5 minutes; stir in pepper and nutmeg. Remove from heat.
Lightly butter a 10 cup (2.5 L) casserole dish. Pour 1/2 cup (125 mL) of the cream into prepared dish. Spoon half of the potato mixture into dish.
Sprinkle with fontina and drizzle over remaining whipping cream. Top with remaining potato mixture.
Cut taleggio (if using) in half crosswise and place cut side down on top of potato mixture, pushing into potatoes slightly, so it is flush with the potatoes. Bake for about 35 minutes or until potatoes are tender when pierced with a knife and tartiflette is golden.
Top 5 Nutrients: Vitamin C ≥23%DV, Vitamin B6 ≥21%DV, Niacin ≥15%DV, Vitamin A ≥14%DV, Thiamin ≥9%DV.