Prepare Your Ingredients:

1. Set up bowls: Place a fine-mesh strainer over a medium bowl and set aside. In a separate small bowl, whisk the egg yolks until smooth; set near the stove.

Make the Butterscotch Base:

2. Combine dry ingredients: In a medium-heavy saucepan, whisk together the brown sugar, cornstarch, and salt until completely combined with no lumps. This step is crucial—break up any brown sugar clumps with your fingers or the back of a spoon.
3. Add dairy: Gradually whisk in the milk and heavy cream, ensuring the mixture is completely smooth with no dry ingredients at the bottom. The mixture will look thin at this stage—that’s normal.
4. Cook the mixture: Place the saucepan over medium heat. Cook, whisking constantly, until the mixture begins to steam and thicken, about 8-10 minutes. You’ll notice it starting to bubble gently around the edges. Continue cooking and whisking until it reaches a thick, pudding-like consistency that coats the back of a spoon.

Temper the Eggs:

5. Temper egg yolks: Once the mixture is thick and gently bubbling, remove from heat. Slowly pour about 1 cup of the hot butterscotch mixture into the bowl with the egg yolks, whisking constantly as you pour. This gradually warms the yolks without scrambling them.
6. Combine everything: Pour the tempered egg mixture back into the saucepan, whisking constantly. Return the pan to medium-low heat and cook, whisking constantly, for 2-3 more minutes until the pudding is very thick and coats the back of a spoon thickly. It should maintain gentle bubbles and reach about 170-175°F if you’re using a thermometer.

Finish the Pudding:

7. Add butter and vanilla: Remove the saucepan from heat. Add the butter pieces, vanilla extract, and whiskey (if using). Whisk until the butter melts completely and the pudding is glossy and smooth.
8. Strain: Pour the pudding through the fine-mesh strainer into the waiting bowl. Use the rubber spatula to press it through, leaving any lumps behind. This step ensures perfectly silky texture.
9. Portion into dishes: Divide the pudding among 6 serving dishes—glass jars, ramekins, or small bowls all work beautifully.

Chill:

10. Prevent skin formation: Press plastic wrap directly onto the surface of each pudding serving to prevent a skin from forming. Refrigerate for at least 3 hours or until completely chilled and set. Overnight is even better—the flavor develops beautifully.
11. Serve: Remove plastic wrap and top with freshly whipped cream and a sprinkle of flaky sea salt if desired. Serve cold and enjoy!