Slice the baguette into one inch slices or wider if you prefer. Lightly toast each side, (toaster oven works great) and lightly butter one side and sprinkle with a bit of garlic salt.
Thinly slice your left over rare roast and pile pieces on top of the baguette. Pop in a preheated toaster oven or regular oven and cook for just a few minutes, long enough to warm the meat. Top with a bit of fresh ground pepper and a few grains of sea salt.
Mix the horseradish and Creme Fraiche together and spoon a bit on the top of each baguette or alternatively simply supply a bowl with the dip in it and a spoon and guests can put their own on.