Position a rack in the middle of the oven and preheat to 375°F. Line a quarter sheet pan (9x13 works too) with parchment and lightly butter or spray the paper so the edges brown evenly.
In a medium bowl whisk together the Kodiak mix, cinnamon, and salt until evenly blended—this aerates the dry ingredients and distributes the spice.
In a separate large bowl combine the milk, eggs, melted butter and vanilla. Whisk briskly until the mixture is smooth and slightly frothy; let sit 1–2 minutes so the butter cools a touch.
Pour the wet ingredients into the dry and fold with a spatula until most lumps disappear—do not overmix. Let the batter rest 5 minutes so the mix hydrates and thickens slightly.
Spread the batter evenly into the prepared pan using an offset spatula or the back of a spoon to a roughly 1/2-inch thickness. Scatter your chosen toppings over the surface and gently press them into the batter so they won’t sink unevenly during baking.
Bake on the center rack for 18–22 minutes, rotating the pan once halfway through, until the edges are golden and a toothpick inserted near the center comes out clean or with a few moist crumbs.
Remove from oven and immediately brush the top with a little melted butter for sheen (optional). Allow to cool 5–7 minutes in the pan so it firms up, then lift the parchment and transfer to a cutting board.
Slice into 6 squares (or 8 smaller pieces) and serve warm with maple syrup, nut butter, or a dollop of Greek yogurt.