1. Heat oven to 350 degrees . Combine confectioners sugar, almond flour, cocoa powder and salt in a food processor. Pulse until combined and the mixture reaches a fine texture, about 30 seconds.
2. Add egg whites to the bowl of a stand mixer fitted with a whisk attachment. Beat on medium-high speed until foamy, about 30 seconds. Add cream of tartar and beat until soft peaks form, about 1 minute. Slowly add granulated sugar and beat until stiff peaks form and the mixture is shiny, 2 to 3 more minutes.
3. Fold 1/3 of the almond flour mixture into the egg whites, being careful not to deflate them. Repeat two more times, then transfer to a pastry bag or resealable plastic bag and snip off corner. Pipe 1-inch circles of batter about 1 inch apart onto two baking sheets lined with parchment paper. Smooth out tops of piped batter.
4. Bake at 350 degrees for 15 to 18 minutes. Cool completely on baking sheet. When cool, spoon a scant teaspoon of the jam in the center of the flat side of a cookie; gently press another cookie on top to form the macaron. Repeat with remaining cookies and jam.