Spread a good amount of softened butter over both sides of each bread.
In a large frying pan, add the bread slices and toast over medium-high heat for a few minutes, turn over, then toast the other side until golden brown on both sides. Remove and place on a baking sheet.
In large frying pan, heat 2 tablespoons butter over medium-high heat. Add the shallots and mushrooms and cook for 5 to 10 minutes or until softened. Transfer to a bowl.
Add the remaining 1 tablespoon of butter to the pan. When the butter has melted, add the reindeer and cook for 5 to 8 minutes or until browned.
Return the mushroom mixture back to the pan and cook 2 minutes more.
Add the heavy cream and juniper berries and cook for 5 minutes or until thickened. Season to taste with salt and pepper.
Preheat a broiler.
Top each toasted bread with a layer of Brunost slices. Place the breads under the broiler, keeping a close watch, and heat the toasts for 1 minute or until the Brunost begins to melt and bubble.
Remove from the broiler and transfer to individual plates.
Divide the reindeer mixture evenly among the Brunost toasts and garnish with fresh parsley or thyme and a few lingonberries, if desired. Serve immediately.
