In a medium saucepan over medium-low heat, combine the maple syrup, sugar, and corn syrup. Stir until the sugar has completely dissolved. If needed, brush down the sides of the pan with a wet pastry brush.

Allow the mixture to boil, stirring for about 10 minutes, until it reaches 115°C (240°F).

Remove from the heat and carefully stir in the heavy cream and butter until smooth and fully incorporated.

Transfer the mixture to a glass jar and let it cool. Once cooled, stir in the chopped hazelnuts and sea salt.

Refrigerate for at least 1 hour, until thickened. (For convenience, the sauce can be prepared up to 3 days in advance.)

In a medium saucepan, whisk together the cornstarch and salt. Gradually add the milk, whisking until smooth and lump-free.

Add the heavy cream, maple syrup, sugar, and egg yolks, and mix well.

Cook over medium-low heat for about 5 minutes, stirring constantly, until the cream thickens enough to coat the back of a spoon.

Continue stirring and watch for bubbles forming. Once it begins to boil, cook for 1 more minute while stirring constantly, then add the butter and mix until fully incorporated.

Strain the cream through a fine sieve and divide into serving glasses or bowls. Cover with plastic wrap, ensuring it touches the surface to prevent a skin from forming, and refrigerate for at least 2 hours.

Remove the creams from the refrigerator and spoon the salted caramel hazelnut sauce over the top. Garnish with a mini stroopwafel cookie and serve immediately.