Blanch the potatoes for 3-4 minutes. Drain the potatoes and set aside. Melt the butter in a Teflon sauté pan. Lay down a layer of potatoes. Top with a thin layer of sautéed onions. Repeat this step again. Finish with a final layer of potatoes. Brown on the stove 5-6 minute. Carefully flip the potato cake in the pan and finish in the oven for 8-10 minutes longer. Serve by cutting into wedges (like a pie). Note: If using new potatoes (thin skinned) do not peel or blanch as they have a lower starch content then a russet potato.