According to the author, Deborah Madison, in this recipe from Vegetarian Cooking for Everyone, the butter melts into the crisp toast and the cheese stays on top.

WARM CROSTINI WITH BLUE CHEESE AND WALNUTS

8 slices baguette or country bread, about 2x3 slices
4 ounces Roquefort, Maytag or Danish blue cheese
3 Tablespoons butter at room temperature
1 teaspoon cognac
1/4 cup finesly chopped walnuts
Freshly milled pepper
Finely chopped parsley

Toast the bread under the broiler until nicely browned on one side, then a little less so on the second. Cream the cheese and butter until smooth, then work in the cognac and three-quarters of the walnuts and season with pepper. Spread on the paler side of the toasts, then broil until the cheese is bubbling. Remove, dust with the remaining nuts, and garnish with parsley. Serve warm.