Pulse the almonds in a food processor until finely chopped. Combine almonds, flour and salt in a medium bowl.
In a saucepan over medium heat, combine the butter, sugar and corn syrup. Bring to a boil while stirring occasionally, to completely dissolve the sugar. Let boil for about a minute, remove from heat and stir in vanilla. Pour the mixture into the almond bowl and stir to combine. Set aside for about a half hour to cool.
Preheat oven to 350 F. Line cookie trays with parchment paper. Using a teaspoon, scoop batter one teaspoon at a time onto the parchment paper. Roll into balls and place with at least 2-3 inches of space between each cookie, as they will spread while baking. Bake one pan at a time for 8-10 minutes, or until flat and a golden brown color. Cool on the baking pan for a few minutes and transfer to a wire rack.
Once all cookies are baked, place 4 ounces of good quality milk chocolate in a microwave safe bowl, and microwave on 50 percent power for one minute. Remove and stir, and heat for additional 30-second increments until melted. Match each cookie with a similar-sized cookie. Flip one cookie over, spoon some melted chocolate on it, spread it around and place the other cookie on top. Set aside to cool and set.
Store in an air-tight container. You may want to place parchment paper between cookies if you are stacking them.