In a large skillet, melt the butter over medium-low heat. Add the onion, carrot, and celery (mirepoix). Cook until softened, stirring occasionally (about 10-15 mins). Set aside to cool.

Using your hands, gently turn over all ingredients until well mixed. Avoid squeezing and over mixing.

Pour out onto a parchment lined baking sheet and shape into a loaf.

Remove the loaf from the oven and cover the entire thing with the glaze.

Remove from oven and let rest for 10 mins to allow juices to redistribute before serving.