Place chopped Belgian dark chocolate in a heatproof bowl. In a small saucepan, heat the heavy cream until it just begins to simmer (bubbles at edge), then remove from heat. Pour the hot cream over the chopped chocolate and let sit 1 minute to soften. Stir gently until smooth and glossy. Stir in the butter, light corn syrup, vanilla extract, and fine sea salt until fully incorporated. Keep warm or transfer to a small insulated container; if the sauce thickens, warm gently over a double boiler or microwave in 10-second intervals, stirring between, until pourable.

Ice Cream & Coffee Layer

Prep espresso mixture

Brew one strong shot of espresso (about 30–40 ml). While hot, stir in the granulated sugar until dissolved. Let cool to room temperature (5–10 minutes). Once cooled, stir in the vodka and coffee liqueur.

Soften ice creams

Let both the vanilla and coffee-flavored ice creams sit at room temperature for 5–8 minutes until scoopable but not melted. Stir each briefly with a spatula to achieve a scoopable, slightly softened texture.

Assemble layers

Using 4 tall sundae glasses or dessert bowls (or 2 large glasses), start by spooning 1/4 cup of vanilla ice cream into the bottom of each glass. Drizzle about 1 tablespoon of the espresso mixture over the vanilla layer (this will soak slightly into the ice cream). Next, add 1/4 cup coffee-flavored ice cream, smoothing lightly. Repeat: add another 1/4 cup vanilla ice cream, drizzle remaining espresso mixture (distribute evenly), then top with 1/4 cup coffee-flavored ice cream. Adjust quantities slightly if using different-size glasses so you have 2–3 visible alternating layers.

Assembly & Garnish

Add chocolate sauce and toppings

Warm the chocolate sauce slightly if needed so it is pourable but not hot. Spoon or drizzle 2–3 tablespoons of the Belgian chocolate sauce over the top of each assembled sundae so it cascades down the layers. Pipe or spoon about 2 tablespoons of whipped cream atop each sundae. Sprinkle each with 1/2 tablespoon chocolate shavings and dust lightly with cocoa powder if using. Finish with three coffee beans per serving and a very small pinch of flaky sea salt over the chocolate for contrast.

Serve

Serve immediately with a long spoon and napkin. If preparing ahead, prepare chocolate sauce and espresso mixture up to 1 day in advance; keep chilled (reheat sauce gently before serving). Do not assemble more than 10 minutes before serving to avoid excessive melting.