Line a standard 9x13-inch sheet pan with parchment paper, making sure it comes up the sides so you can grab it easily later. In a medium bowl, whisk together your 2 cups of Greek yogurt with 1/2 cup honey until you get a smooth, creamy base with no lumps. Stir in the 2 tablespoons of fresh lemon juice and 1 teaspoon of lemon zest until everything's combined.
Add 1/2 teaspoon of orange blossom water and 1/4 teaspoon of sea salt to your yogurt mixture and stir well. Taste it real quick—this is where you decide if you want it sweeter or more tangy, so adjust the honey or lemon juice if needed. I personally think this stage is the best time to dial in the flavor since you can't fix it after it freezes.
Spread the yogurt mixture evenly across your prepared sheet pan using an offset spatula or the back of a spoon. You want it roughly 1/4 inch thick and reaching into all the corners—don't worry if it's not perfectly even since bark never is anyway. Make sure the layer covers the whole pan so you get nice-sized pieces when you break it apart later.
Scatter 1 cup of fresh blueberries evenly across the yogurt base, pressing them down gently so they stick but don't disappear completely. In a small bowl, melt 1 tablespoon of coconut oil with 2 tablespoons of butter, then toss in 1/4 cup of rolled oats, 1/4 cup of chopped pistachios, and 1/4 cup of chopped almonds. Drizzle this nutty mixture all over the yogurt in random clumps—don't go for perfect coverage.
Pop the whole sheet pan into your freezer uncovered and set a timer for exactly 4 hours. Don't panic if it looks a little soft after the first hour—it'll firm up as it goes. I usually check around hour three to make sure nothing's slid around, though honestly it's pretty hard to mess up at this point.
Once everything's frozen solid, take the sheet pan out and let it sit on the counter for about 2 minutes so the parchment releases easily. Lift the whole frozen blueberry yogurt bark slab out onto a cutting board using that parchment paper as your helper. Break it into rough pieces with your hands—they won't be perfect and that's exactly the vibe we're going for here.
Transfer your bark pieces to an airtight container lined with parchment to prevent sticking, then return to the freezer for storage. These'll keep perfectly for up to two weeks, which honestly feels impossible but I've tested it multiple times. Grab a piece whenever you need a sweet, cold, protein-packed moment.