Slice the baguette crosswise into 1/4 inch thick slices, cutting diagonally so that you get the longest slices possible ( see the shape of the slices in the photos)
In a small bowl, stir together the butter and olive oil.
If you want any flavor additions, mix them into the butter compound now.
Use a brush to spread the butter compound onto the top of each slice of bread. Make sure that you are only putting on a thin layer otherwise the crostini won't crisp up in the oven, they will be slightly spongy instead.
Place the slices onto a cookie sheet buttered side up.
Bake in the preheated oven for 8 to 10 minutes, until they are toasted and hardened.
Remove and cool completely before storing in a container or plastic bag at room temp.