In medium sauté pan, melt 1 stick butter and add brown sugar. Stir to combine and cook 1 minute. Add 2 tablespoons cream, stir and cook an additional minute. Add apple and sprinkle of salt, cover with lid and cook 4-5 minutes. Remove from heat and add blueberries and cover with lid again to keep warm and soften blueberries.
Heat fry pan over medium-high heat and add 1 tablespoon butter to melt. In large bowl, whisk eggs, remaining 2 tablespoons cream, nutmeg and vanilla extract 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.