Melt butter in a small saucepan over medium heat. Add pecans and stir until the nuts are lightly toasted and fragrant, about 1 minute. Remove the pan from the heat; stir in brown sugar.Advertisement
Stir milk, cornstarch and salt together in a small cup; whisk into the brown sugar mixture. Return to the heat and whisk until the sauce is simmering and thick, about 1 minute. Serve warm over frozen yogurt.