First, preheat your oven to 350°F (175°C). A properly heated oven is key to a well-cooked dish.

Next, grab those lovely squashes. Halve them and scoop out a bit of the flesh to make a small cavity for the filling. Don't discard those scraps! They can add depth to soups or stir-fries later. Set the hollowed-out squashes aside.

In a medium saucepan, melt the butter over medium heat. Once it’s bubbling, add the flour. Stir it continuously to create a roux—this should take about 2 minutes. Gradually whisk in the milk to avoid lumps. Keep stirring until the sauce thickens. This part might test your patience, but trust me, the result is worth it!

Now spice things up! Add salt, pepper, and Dijon mustard into your sauce. Then incorporate the shredded cheese, allowing it to melt luxuriously into your mixture. It’s like a hug for the squashes.

Using a spoon, fill each halved squash with your dreamy cheese mixture. Don’t skimp here; pack it in! After that, sprinkle the crushed butter crackers on top for an added crunch.

Arrange the stuffed squash halves in a baking dish. Cover them with foil to prevent them from drying out. Bake for about 25 minutes. After that, remove the foil and let it bake uncovered for an additional 10-15 minutes. This will create a beautiful golden crust.

Finally, when you pull your squash out of the oven, sprinkle with fresh parsley. Not only does it add color, but it also brings a fresh taste that complements the richness of the dish perfectly.