Preheat oven to 350F. Line an 8-by-8-inch pan with aluminum foil and leave overhang, spray with cooking spray; set aside.
In a large mixing bowl, whisk together first 5 ingredients (through vanilla).
Add the next 4 ingredients (through optional salt), and stir until just combined; don’t overmix.
Turn dough out into prepared pan, using a spatula or fingers to smoosh dough into corners. Smooth top lightly with a spatula.
Arrange chocolate chunks in rows (if desired) or simply sprinkle them evenly over the surface; press chunks is lightly, enough so they’re anchored and bake into the dough or will be prone to falling out of the baked sticks.
Bake for 18 to 20 minutes (sticks in photos were baked 19 minutes; for crispier sticks, add 2 to 5 minutes to baking time), or just until set in the center; don’t overbake because sticks firm up as they cool. Allow to cool completely in pan before lifting out with foil overhang.
Place the large slab of baked dough on a cutting board and with a pizza wheel or sharp knife, cut into sticks. In order to get clean lines and very neat looking sticks as shown in the photos, you must wait for slab of dough to cool completely before slicing. Sticks will keep airtight at room temperature for up to 5 days or in the freezer for up to 3 months.