Nutella Thumbprint Cookies

Ingredients

• 1 1/4 cups flour
• 3/4 cup cocoa powder
• 1 tsp baking soda
• 2 tsp cornstarch
• 3/4 tsp salt
• 1/2 cup 1 stick butter, softened
• 1/2 cup brown sugar (packed)
• 1/2 cup granulated sugar
• 1 egg + 1 egg yolk
• 1 1/2 tsp vanilla
• 1 jar Nutella (you may need less, but just to be on the safe side!)
• assorted sprinkles (optional)