Prepare the Foundation : Line a quarter-sheet pan with a sheet of parchment paper, ensuring there is a slight overhang on the sides to use as handles later.
Infuse the Spices : In your medium mixing bowl, whisk together the fine sea salt, ground cinnamon, nutmeg, and cardamom. This step blooms the spices, awakening their aromas before they are mixed into the yogurt.
Whip the Yogurt Base : Add the Greek yogurt, honey, and vanilla extract to the bowl with the spices. Stir gently with the silicone spatula until the mixture is smooth, uniformly colored, and no streaks remain.
Spread the Mixture : Pour the seasoned yogurt onto the center of your prepared pan. Use the spatula to guide the mixture into an even, rectangular layer, roughly ¼-inch thick.
Create the Apple Marble : Drop small spoonfuls of the cinnamon applesauce randomly over the yogurt base. Take the tip of a small offset spatula or a skewer and drag it through the dollops to create an elegant marbled pattern.
Garnish and Set : Evenly distribute the pecan and oat granola over the surface of the swirled yogurt. Lightly press the granola to help it adhere.
Freeze Until Firm : Carefully transfer the pan to the freezer. Let it set until completely solid, which should take at least 4 hours. The bark is ready when it snaps cleanly.
Portion and Serve : Lift the entire frozen slab out of the pan using the parchment paper handles. Place it on a cutting board and break it into 8 large, rustic pieces. Serve immediately for the best texture.