Not to get too "National Treasure" here, but ... tucked away in the Library of Congress, you can find a well-worn handwritten vanilla ice cream recipe that, like the aid our Founding Fathers received during the Revolutionary War, came from France.

It was brought back to this country by Thomas Jefferson, who encountered the delicious frozen treat during his time as ambassador to France in the 1780s, and then famously served it to guests at the President's House. The recipe is believed to have originated with Adrien Petit, Jefferson's French butler, who accompanied him back to America.

(MORE: Founding Fathers were weather geeks too — here's proof)

Of course, Jefferson's July looked a little different than ours. There were no heat indices, no air conditioning and no trips to the freezer aisle for relief. But the impulse to cool down with something cold and sweet has been a part of this country almost as long as it's been a country.

This summer, as temperatures across the country push well past 100°F in many places, we're going back to basics with Jefferson's original recipe, followed by a modern adaptation by food historian Marie Kimball. With National Vanilla Ice Cream Day falling on July 23, there's never been a better time to try it.

Thomas Jefferson's Vanilla Ice Cream

From Thomas Jefferson's original handwritten recipe, preserved at the Library of Congress

Makes: About 2 quarts

Ingredients:

• 2 bottles (quarts) of good cream
• 6 egg yolks
• ½ lb. sugar (about 1¼ cups)
• 1 stick of vanilla

Instructions (in Jefferson's own words):

1. Mix the yolks and sugar.
2. Put the cream on a fire in a casserole, first putting in a stick of vanilla. When near boiling, take it off and pour it gently into the mixture of eggs and sugar.
3. Stir it well. Put it on the fire again, stirring it thoroughly with a spoon to prevent it sticking to the casserole.
4. When near boiling, take it off and strain it through a towel.
5. Put it in the Sabottiere*, then set it in ice an hour before it is to be served. Put into the ice a handful of salt. Put salt on the coverlid of the Sabottiere and cover the whole with ice.
6. Leave it still half a quarter of an hour. Then turn the Sabottiere in the ice 10 minutes. Open it to loosen with a spatula the ice from the inner sides of the Sabottiere.
7. Shut it and replace it in the ice. Open it from time to time to detach the ice from the sides. When well taken, stir it well with the spatula.
8. Put it in moulds, justling it well down on the knee. Then put the mould into the same bucket of ice. Leave it there to the moment of serving it.
9. To withdraw it, immerse the mould in warm water, turning it well till it will come out and turn it into a plate.

*A Sabottiere is an ice cream maker — in its simplest form, a mould or small bucket.

Modern Version
Adapted by food historian Marie Kimball

Ingredients:

• 6 egg yolks
• 1 cup sugar
• Pinch of salt
• 1 quart heavy cream
• 2 teaspoons vanilla extract

Instructions:

1. Beat the yolks of 6 eggs until thick and lemon colored.
2. Add gradually 1 cup of sugar and a pinch of salt.
3. Bring to a boil 1 quart of cream and pour slowly on the egg mixture.
4. Put in top of a double boiler and when it thickens, remove and strain through a fine sieve into a bowl.
5. When cool, add 2 teaspoons of vanilla.
6. Freeze as usual, with one part salt to three parts ice. Place in a mould, pack in ice and salt for several hours. For electric refrigerators, follow usual directions but stir frequently.