Start by placing the vanilla extract in a large bowl. Set a fine mesh strainer over the bowl.

In a large saucepan, combine the whole milk, corn starch, egg yolks, sugar, and salt. Whisk until thoroughly mixed.

Over medium heat, bring the mixture to a boil while whisking constantly.

Taste and adjust sugar or salt as needed before it gets too hot.

Once it bubbles, reduce heat and cook for an additional 30-45 seconds while whisking vigorously. Remove from heat and strain the custard into the bowl with vanilla.

Cut rectangles of lemon pound cake about 1/2 inch thick and fit them in the bottom of a 9'x13' glass baking dish.

Drizzle the cream sherry evenly over the pound cake.

Spread a layer of raspberry jam over the pound cake.

Add another layer of pound cake, drizzle with more sherry, and cover with another layer of jam.

Carefully pour the custard over the trifle, filling any gaps.

Cover the custard with roughly 1/2 inch of whipped cream made by whipping the heavy cream with sugar, salt, and vanilla until soft peaks form.

Cover the trifle with plastic wrap and chill in the refrigerator for several hours or overnight.

Once chilled, serve in generous slices, optionally topping each slice with a maraschino cherry.