POUR 2 cups of milk and ½ cup cream into a 4 quart sauce pan.

STIR in ¼ cup granulated sugar and the salt. Stir briefly to combine.

WARM over medium heat until the liquid gets steamy and the sugar has dissolved. Stir occasionally. The liquid should not boil, but should reach between 180° and 190°F.

PREPARE a cornstarch slurry. Slowly whisk the cornstarch into the cold water. Stir until it is a thick slurry. Set aside until the milk/cream mixture is ready.

SEPARATE the yolks from two room temperature eggs. Use the egg whites in another recipe. Gently whisk the yolks with a fork. Set aside.

When the milk/cream mixture is steamy, SLOWLY DRIZZLE the cornstarch slurry into the hot liquid, whisking constantly. It will start to thicken immediately.

Continue to WHISK constantly over medium heat until the mixture is thickened and starts to bubble. Be patient. Depending on your stove it may take between 15 and 30 minutes. (Gas stove tops are quicker and electric stove tops take longer. Sauce pan quality also plays a role.)

After it begins to bubble, STIR for one more minute. Then remove the pan from the heat and allow it to cool for 1 minute.

TEMPER the egg yolks. Spoon a small amount (1 or 2 teaspoons) of hot pudding into the yolks and whisk with the fork. Continue to add the hot pudding in small amounts, whisking constantly until half of the pudding is in the yolks.

WHISK the egg yolk/pudding mixture back into the pan (that is still off heat) until it is completely incorporated.

RETURN the pan to medium heat and whisk constantly until the pudding begins to bubble again. Cook for 1 minute.

REMOVE the pudding from the heat and turn off the stove.

POUR the pudding through a fine-mesh sieve or strainer in to a bowl with an airtight lid (even if you do not see lumps).

STIR in the butter and vanilla.

COOL the pudding, stirring every few minutes. The pudding will continue to thicken as it cools.

When the pudding has cooled (20 or 30 minutes), COVER pudding with a piece of plastic wrap by pressing the plastic wrap directly on the surface of the pudding. This prevents a skin from forming on the pudding as it cools.

SECURE the lid to the top of the container and place it in the refrigerator until completely chilled, about 2 hours.

WHIP the cream. Place 1 cup of heavy cream in a chilled bowl and stir in 2 tablespoons of granulated sugar. Using a hand or stand mixer with a wire whip, whip the cream until it forms medium peaks.

REMOVE the pudding from the refrigerator and use a hand mixer to mix until smooth. It will be slightly thick.

BLEND in the sour cream with a hand mixer.

FOLD in the whipped cream. Do not overmix.

LAYER the cookies on the bottom of a container with an airtight lid. Reserve a few cookies to use as a garnish, if desired.

SLICE a banana in ¼ inch disks and layer the disks on top of the cookies. (Slice the bananas as needed as you work.)

SMOOTH a thick layer of banana pudding over the banana slices, covering them completely.

REPEAT layering cookies, banana slices, and pudding until the container is ¾ of the way full, ending with the pudding layer.

COVER with plastic wrap and secure the lid. Chill overnight, and up to 36 hours.

TO SERVE, remove the pudding from the refrigerator. Let it sit on the counter for 5 minutes.

REMOVE the lid and the plastic wrap. Crush the extra cookies or add several fresh banana slices to garnish.

SERVE immediately.