Add oil to a 2 quart sauce pan and heat.

Sauté onions and celery for 5 minutes.

Add smashed garlic and sauté for 1 minute.

Add salt, pepper, thyme, and parsley and stir.

Cover with chicken stock and braise on simmer until the celery is tender.

Heat 1 cup of chicken stock.

Heat 1 Tbsp. of butter in a small sauce pan until it stops frothing.

Sift in 1 Tbsp. of flour, whisking continuously.

Once the roux is a golden color, whisk in 1 cup of hot chicken stock.

Reduce by about half until it coats the back of a spoon.

Add 1 Tbsp. of butter to a small, hot pan.

Sauté ½ cup of diced celery until tender but still firm.

Purée the celery mixture with the stock and return to the sauce pan.

Add ½ cup of velouté and stir.

Set the heat under the pan to simmer.

Heat ½ cup of cream in a small sauce pan.

Whisk in an egg yolk.

Slowly add the cream mixture to the celery base and whisk together.

Increase heat to low and reduce to desired thickness.

Before serving, toss in the sautéd diced celery and mix.

Dish into bowls and sprinkle chopped young celery leaves on top.

Serve with toasted crostini.