The Mornay sauce is a classic cheese sauce made by enriching a standard béchamel sauce with Gruyère and Parmesan cheese. It's an ideal accompaniment for eggs (Eggs Mornay is a French classic) as well as pasta and vegetables.
In classical cuisine, there were variations on the Mornay where instead of making it with a béchamel base as we do here, it was made with chicken or fish stock — making it a variation on the velouté sauce instead.
(see also: The Five Mother Sauces)
This makes sense if you're serving the finished sauce with chicken or fish or seafood. Indeed, some people might find the standard Mornay sauce to be a bit rich for fish and seafood (then again, see Lobster Mornay).
In the classic French tradition, you cannot have too much cream, butter, or cheese. On the other hand, in Italian cooking, it's considered an abomination to serve fish with cheese. And so it goes. Maybe someone can get a French chef and an Italian chef to sit down and decide whose cuisine is superior. They can get back to us in a couple of centuries maybe.
In the meantime, you have my permission to serve this basic Mornay sauce with chicken and fish. But feel free to experiment with the chicken and/or fish veloute versions if you like.
- 2¾ cups whole milk (warm but not hot), divided
- 35 grams unsalted butter (slightly more than ¼ stick), plus an additional 1 Tbsp
- 30 grams all-purpose flour (around 1/3 cup)
- 1 bay leaf
- ¼ onion, peeled
- 2–3 whole cloves
- 2 oz grated Gruyère cheese
- 2 oz grated Parmesan
- In a heavy-bottomed saucepan, melt the 25 grams of butter over medium-low heat, then stir in the flour to form a roux. Cook the roux for 2–3 minutes, stirring frequently until most of the water has cooked out (it'll bubble less), which also allows the raw flour taste to cook off.
- Slowly add 2½ cups of the milk while whisking or stirring so that the liquid is incorporated into the roux without forming lumps.
- Stick the cloves into the onion and add to the sauce along with the bay leaf. Simmer for about 20 minutes, until it's reduced by about 20 percent.
- Remove the bay leaf and the onion, strain the sauce through a fine mesh strainer or a colander lined with cheesecloth. Make sure you retrieve as many whole cloves as you originally added.
- Return the sauce to the pan. Add the Gruyère and Parmesan cheeses and stir until the cheese has melted.
- Remove from heat, stir in the remaining butter and adjust consistency with the additional milk if necessary. Serve right away.