Preheat the panini grill to medium-high heat.
For each sandwich: Slice off the doomed top of a baguette portion to create a flat grilling surface.
Split the baguette to create top and bottom halves. Spread a layer of pesto inside each baguette half. On the bottom half layer some mozzarella, tomatoes, basil, and more mozarella. Close the sandwich with the top baguette half.
Grill two panini at a time, with the lid closed, until the cheese is melted and the bread is toasted, 5 to 6 minutes .