- With the rack in the middle position, preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
- On the baking sheet, toss the beets with the oil. Season with salt and pepper. Spread the beets out on the baking sheet in an even layer. Cover with parchment paper. Cook for 15 minutes or until tender. Remove the top piece of parchment paper. Drizzle with the lemon juice and let cool.
- Meanwhile, cut each slice of bread into two 3 x 1 ½-inch (8 x 4 cm) rectangles.
- In a skillet over medium heat, brown the bread on each side in the butter. Let cool.
- In a bowl, combine the mayonnaise and mustard. Spread over the croutons. Fold a few beet slices together to form small roses and place them side-by-side on the croutons. Top each crouton with slices of goat cheese and sprinkle with the hazelnuts and tarragon.