In a small saucepan over medium-low heat, add milk,stock, and bay leaf and heat until tiny bubbles appear around the edges, about 5 minutes. Remove from heat and set aside for 5 minutes. Discard bay leaf.

In a medium saucepan, melt the butter over low heat. Whisk in the flour and let bubble, without browning, for 1 minute. Whisk in the hot milk and stock mixture. Bring to a simmer. Cook, stirring often, until the sauce thickens and no taste of raw flour remains, 2 to 3 minutes. Season with the salt and white pepper. Remove from the heat. Set the sauce aside.

To cook fresh boiling onions, bring a large pot of water to a boil over high heat. Add the onions and cook pearl onions for 1 minute and boiling onions for 2 minutes. Drain well and rinse under cold running water. Using a small sharp knife, trim off the tops and bottoms of the onons, peel them and pierce the side of each onion with tip of knife, this helps the onions to retain their shape. Place th onions in a skillet and add 2 cups of chicken stock and enough water to barely cover onions. Bring to a boil over high-heat, cover and reduce heat to medium. Cook until onions are tender when pierced with knife tip, about 8 minutes for pearl onions and 12 minutes for boiling onions. Drain well reserving the broth to mix with milk to make the creamed onion sauce.

Add the onions to the hot sauce and mix well. Transfer to a warm serving dish and serve immediately.