Preheat oven to 425. Line a baking sheet with foil and lightly spray with cooking spray; set aside.
Slice brussels sprouts into discs, gently separating some of the layers with your fingers.
In a mixing bowl, combine sliced brussels sprouts, olive oil, lemon zest, lemon juice, garlic, salt and pepper and toss until brussels sprouts are coated and zest, garlic, salt and pepper are well mixed.
Spread brussels sprouts on prepared baking sheet and roast for 15 minutes, tossing halfway.
Spread butter on both sides of sourdough slices and toast over medium heat, flipping sides until you get your preferred toastiness.
Spread hummus on each slice.
When brussles sprouts have finished, split between the two slices of hummus toast. Garnish with baisl, panko crumbs, red pepper flakes and enjoy immediately!