Whisk the egg yolks in a 2 cup measure or small bowl.
In a 4 qt saucepan, add the cream, sugar, maple syrup, and salt. Bring to a boil, stirring consistently over medium low heat.
Stir in the chocolate chips until melted and the mixture is smooth.
While whisking the egg yolks, pour and stir about 1/2 of the chocolate mixture into the whisked eggs. Pour immediately back into the saucepan, stirring constantly. Cook over low heat, stirring continually for 2 minutes more.
Remove from the burner. Stir in the coffee extract and vanilla. Using a sieve over a bowl, strain the mixture. Set aside to cool. Move to refrigerator to finish cooling for 10-15 minutes.
Whip the cream using an emulsion blender, hand mixer, or stand mixer until it's starting to thicken. Add the 1 tablespoon of sugar and continue whipping until thick but soft and pillowy.
Reserve ½ cup of whipped cream to decorate the top. Gently fold the remaining cream into the cooled mocha mixture. Spoon in to the chilled crust and spread to smooth.
Add whipped cream edging chocolate shavings or nuts as desired. Refrigerate for 3-4 hours or freeze for 1-1½ hours before serving.