Step 1

Melt butter in a large pot over medium heat. Cook and stir leeks, garlic, salt, and pepper in the hot butter until leeks are tender and lightly browned, about 15 minutes.

Step 2

Stir chicken broth and cornstarch together in a bowl until cornstarch is dissolved; pour over the leek mixture. Add potatoes to the broth mixture and bring to a boil; season with onion powder and garlic powder. Reduce heat, add half-and-half to broth mixture, and simmer until potatoes are tender, about 30 minutes.

Step 3

Remove pot from heat and blend soup using a hand blender until smooth; season with salt and pepper.