Preheat the oven to 450 degrees Fahrenheit. Line a baking sheet with aluminum foil.
Cut slits three-quarters of the way through a baguette about 1-inch apart, making sure not to cut all the way through the baguette.
In a bowl, mix together the butter, jalapeno, garlic and salt. In a separate bowl, mix together the cheeses. Spread a little of the butter mixture into each of the slits, and press the cheese mixture into the slits, using all the cheese and butter and filling all the slits.
Put the baguette onto the baking sheet lined with foil and place in the oven. Bake for 10 to 15 minutes, or until the cheese is bubbling and the baguette is golden brown.