Preheat the oven to 210°C/410°F.
First prepare the roasted garlic: slice the top off the whole bulb of garlic to expose the cloves inside (see photos in the blog post above). Place the garlic bulb on a square of baking paper or foil.
Drizzle the olive oil over the garlic and season with salt and pepper. Cover the bulb with the paper or foil and bake for 25-30 minutes until the garlic is soft.
Slice the baguette or ciabatta in half lengthwise and place on a baking tray.
Prepare the garlic butter: add the softened butter, diced jalapeños, chopped spring onions and mayonnaise to a medium bowl. Remove the garlic from the oven and squeeze out the garlic cloves into the bowl.
Mix the garlic butter together, ensuring the garlic cloves are well mashed up.
Grate the mozzarella and cheddar cheeses and transfer to a medium bowl. Mix them together to combine.
Generously spread the garlic butter mix over each slice of the baguette, ensuring that the butter is spread up to the edges.
Top each slice of baguette with the cheese mixture and some extra jarred jalapeños (optional).
Bake the cheesy jalapeño garlic bread for 10-12 minutes until golden and bubbling. Enjoy!