Preheat oven to 450.
Heat a large skillet over medium-high. Add sausage and cook, breaking apart with a wooden spoon, until sausage is cooked and fat is rendered (meaning that the fat has separated from the meat), about 5 minutes.
Using a slotted spoon, transfer the sausage to paper towels to drain off any remaining fat.
Add scallion whites and garlic to the skillet. Cook until fragrant and soft, about 20 seconds. Stir in beans and cook 1 minute. Add broth, spices, and jalapenos (if using). With a potato masher or the back of a spoon, mash beans until they are "chunky-smooth." (That's Emeril's term, not mine.)
Reduce heat to medium, and cook until heated through, 1 to 2 minutes.
Assist your small person in spreading half of the tortilla chips in the bottom of a large baking dish. Top with half of the beans, half of the sausage, and allow your helper to sprinkle on half of the cheese. Repeat with remaining ingredients.
Bake until cheese melts and nachos are hot, about 5 minutes.
Assist your helper in sprinkling scallion greens over the nachos.
Serve with sour cream and salsa.