Preheat oven to 350ºF. Line an 8-inch square baking pan with parchment paper so that opposite ends overhang by a couple of inches.

To make the crust, place hazelnuts, oats, flour, cinnamon and salt in a food processor. Pulse until mixture resembles sand. Add almond butter, syrup, and vanilla. Pulse again until ingredients are combined and mixture comes together when pinched. If it’s too dry, add a little water. Empty contents of food processor bowl into the prepared baking pan. Press firmly with hands or the bottom of a dry ingredient measuring cup to even out. Place pan in oven and bake for about 20 to 25 minutes. Crust is done when lightly browned and firm to the touch. Remove from oven and let cool. Crust can be made several days in advance.

To make the ganache, put the chopped chocolate and coconut milk in a heat safe bowl and set over a pot filled halfway with water. Bottom of bowl should not touch water. Bring the water to a simmer and gently whisk until the chocolate is about three quarters melted. Remove bowl from heat; chocolate will continue to melt.  Add vanilla and salt. Whisk until smooth.

When crust is cool, pour chocolate ganache on top and smooth with a spatula. Sprinkle chopped hazelnuts on top and press them very lightly into the chocolate. Put pan in refrigerator for a minimum of an hour, until the ganache hardens.

Remove pan from refrigerator. Slide a sharp knife around the edges without the parchment paper overhang. Carefully pull up on both ends of the parchment, lifting out the tart. Place on a cutting board. Optional step: Dust with cocoa powder by placing a tablespoon of powder into a fine mesh sieve or trainer and tap over the tart to cover. Use a long, sharp knife to cut into 1 1/2 to 2 inch squares. Store covered for up to a week.