Heat some butter in a small pan over medium heat.
Add the nuts and toast for a few minutes. Stirring often and making sure the nuts don't burn.
Add the brown sugar to pan and stir in with the buttered and toasted nuts. Melt down about 3-4 minutes, stirring often.
Sprinkle the mixture with some Kosher salt. Remove from heat.
Divide this mixture between the grilled, pitted peaches and serve warm.