Peel fresh horseradish as you would a carrot, and grate on the fine side of a box grater.
Preheat oven to 450°.
Combine first 4 ingredients in a small bowl. Chill.
Cut baguette into 1/4-inch slices. Place slices on an ungreased baking sheet. Bake 2 minutes; remove from oven. Turn slices, and spread evenly with horseradish mixture. Bake 1 minute or until butter is melted. Serve immediately.