Place garlic cloves in oven-proof small glass dish or bake ware and drizzle with a little olive oil. Cover container and roast garlic in 350 degree preheated oven for 25-30 minute, until soft. Do not burn garlic. Remove from oven and let cool.
Clean leek in cold water. Sand and dirt gets down between the layers of a leek, so make sure you thoroughly clean it. Loosen the leafy layers and run under cold water until all grit is removed. Cut leek coarsely into about 1/4 inch slices.
Prepare snap peas by boiling briefly, 1-2 minutes, or steaming in a covered container in the microwave for 1 minute. Shuck some peas from the pods and discard pods. Set aside.
In a non-stick skillet, cook sliced leek in 2 tablespoons of butter and cloves of roasted garlic for 1 minute over low heat. Add remaining butter to the skillet and continue cook another 2 minutes over medium-low heat allowing butter to brown a bit. Add the sugar snap peas and heat another half a minute. Remove skillet from heat and let veggies steep in brown butter sauce until ready to use.
Meanwhile, prepare mashed potatoes according to package directions. Remove potatoes from bag and place in serving bowl. Pour burnt butter, leek, pea, and garlic sauce over potatoes and gently stir to incorporate.
Season potatoes to your liking and serve alongside your favorite meat.