Preheat the oven to 350 F.
In a medium mixing bowl, add the softened butter, flour, powdered sugar, brown sugar, cocoa powder, and salt. Using a mixer, whip the ingredients until entirely combined and smooth.
Put the sliced almonds in a separate, small bowl.
Using a 1.5 TB cookie scoop, drop each ball of cookie dough into the sliced almonds and roll to partially coat in almonds. You will have to press slightly to get the almonds to stick.
On a parchment paper covered baking sheet, place 12 cookies equally spaced apart and, using a teaspoon, make indents in the middle of each cookie.
Bake at 350F for 10 minutes.
After the cookies are out of the oven, use a different teaspoon to re-make the indents in the cookies, as they will have risen slightly.
Wait for the cookies to cool, roughly 30 minutes.
Once the cookies have cooled, make the ganache: warm the cream until it is incredibly hot, but not yet starting to boil. In a separate bowl, have your chocolate chips ready.
Pour the hot cream on top of the chocolate chips and stir until the chocolate is completely melted.
Fill each thumbprint with ganache. The longer that the cookies sit, the more the ganache will set.
Enjoy!