Preheat oven to 450° F (230° C). Line a large rimmed baking sheet with parchment paper.
To a large rimmed plate, add the Breadcrumbs, and ½ teaspoon each of Garlic, Onion, and ¼ teaspoon of Salt. Combine well and set aside.
In a large bowl, whisk together the Flour and ½ teaspoon each of Garlic, Onion, and Salt. Now pour in the Milk and Water and whisk to combine well. The batter should be thick, but still pourable. If it's too thick, add a few tablespoons of water.
Place a handful of Cauliflower to the bowl and toss to coat well. Lightly shake off excess batter of each piece and place in the breadcrumbs.(to make it faster, I put a bunch of battered cauliflower on a cooling rack to drain with parchment paper underneath) Gently roll around to coat well and place on baking sheet, leaving room in between each piece. Place in the oven for 20 minutes to turn golden and crisp. Flip over pieces at the halfway mark.
Remove from oven and brush each piece with BBQ sauce. (*I prefer to brush on the sauce because they lose their crispness if you fully immerse them - you can add more after baking or serve with bbq sauce as a dip) Place each piece back on your baking sheet and leave a few inches in between. Bake for another 8-10 minutes to caramelize the sauce.
Serve immediately with dipping sauces of your choice. Enjoy!