In a medium sauté pan, melt 1 stick butter and add brown sugar. Stir to combine and cook for 1 minute. Add 2 tablespoons cream, stir and cook for an additional minute. Add apple and sprinkle of salt, cover with lid and cook for 4-5 minutes. Remove from heat and add blueberries and cover with lid again to keep warm and soften blueberries.
Heat a fry pan over medium high heat and add 1 tablespoon butter to melt. In a large bowl, whisk eggs, remaining 2 tablespoons cream, nutmeg and vanilla together until mixed well and frothy. Dredge bread in egg mixture on both sides and fry one or two pieces of bread at a time, flipping after 2-3 minutes each side.
Top French toast slices with apple and blueberry mixture.