Step 1
Pour cream into a large bowl and set a mesh strainer over the bowl. Whisk egg yolks together in a separate bowl.
Step 2
Heat milk sugar and corn syrup together in a saucepan over medium-low heat until milk begins to steam about 5 minutes. Slowly pour about 1/2 cup heated milk into the egg yolks whisking constantly. Scrape egg yolk mixture into the saucepan with a heatproof spatula.
Step 3
Cook and stir milk mixture constantly with the spatula scraping the bottom of the saucepan often until mixture thickens and coats the spatula about 10 minutes. Remove saucepan from heat; pour mixture through the mesh strainer into the cream.
Step 4
Stir 3/4 cup maple syrup coarse salt and vanilla into cream mixture then place the bowl over a larger bowl of ice water; stir to cool to room temperature. Chill mixture in the refrigerator about 2 hours.
Step 5
Preheat oven to 275 degrees F (135 degrees C). Spread walnuts onto a baking sheet.
Step 6
Toast walnuts in the preheated oven until they turn golden brown and become fragrant about 15 minutes. Set nuts aside to cool to room temperature. Chop nuts coarsely.
Step 7
Heat the 1/2 cup plus 1 tablespoon maple syrup in a saucepan until it comes to a boil. Stir in walnuts and return to a boil. Stir nuts for 10 seconds remove from heat; set aside to cool completely. The nuts will be wet and sticky when cooled.
Step 8
Remove cream mixture from the refrigerator pour into your ice cream maker and freeze according to manufacturer's instructions. During the last few minutes of churning stir in wet walnuts.