Preheat the oven to 350ºF. Lightly grease a 9-inch round cake pan and line it with a parchment paper round. Set aside.
Add the Ritz crackers, ½ cup (60g) walnuts, and ½ cup (60g) toasted coconut flakes to a gallon freezer bag. Use a rolling pin or meat mallet to pound the mixture into a coarse meal. Set aside.
Melt 6 tablespoons (84g) butter in a small pot over medium heat. Once melted, add ½ cup (100g) light brown sugar. Stir to combine. Cook over medium heat for 3 minutes, stirring occasionally, until the sugar blends into the butter and the mixture darkens slightly in color.
Reduce the heat to low and add 2 tablespoons (30g) heavy cream and 1 teaspoon vanilla extract. Whisk until smooth and simmer for 1 minute. Turn off the heat and stir in the Ritz cracker mixture until completely combined.
Pour the mixture into the prepared cake pan and smooth it into an even layer. Transfer to the refrigerator for 15 minutes.