Preheat the oven to 400 degrees F.

In a food processor or chopper, pulse the walnuts until they are finely chopped, and the pieces are about the size of breadcrumbs.  

Place the chopped nuts in a large bowl and add the remaining ingredients, tossing together with a fork.  

Pour the milk into a small pot and place over medium heat until small bubbles form around the edges.  

Whisk the egg yolks, maple syrup, cornstarch, and salt together in a bowl until combined.  

Slowly pour the hot milk over the egg mixture, while whisking, to warm the eggs.  

Cook, stirring constantly, until the mixture becomes very thick.  

Turn off the heat, add the vanilla, and strain through a fine-mesh sieve into a heat safe bowl.  

Place plastic wrap directly onto the surface and refrigerate for 2 hours.

Spread the maple custard in the walnut tart shell.  

Warm the apple slices in the microwave until pliable.  

Roll a slice of apple into a tight spiral and stand it up vertically in the custard.  

Continue to arrange apple slices in a concentric pattern around the first one, building a rose pattern.

Repeat until the top of the tart is completely covered with apple roses.  

Brush honey over the apples, for shine (optional).