In a skillet over medium-high heat, melt half of the butter. When the butter has stopped foaming, add asparagus, and season with salt and pepper. Cook, turning often, until all sides are lightly browned. Remove asparagus from heat, and set aside.
On the bottom halves of the baguette, make two layers of cheese and ham, sandwiching 4 spears of asparagus between the layers. Smear the top half of each baguette with Dijon and jam, and cap the sandwiches.
In the skillet over medium-low heat, melt remaining butter. Once the butter has stopped foaming, add one of the sandwiches to the skillet. Press the sandwich with something heavy, such as a foil-wrapped bottom of another cast-iron skillet, a full kettle, or a foil-wrapped brick. Cook the sandwich for about 2 minutes, until the cheese softens; then flip, weight the sandwich again, and cook for an additional 2 minutes. Repeat process with the second sandwich, and serve immediately.