Make the cookie base: Preheat the oven to 350 degrees. Prepare a 9 inch round cake pan by lining with parchment paper cut into a circle or spraying with non-stick cooking spray. {I lightly brushed mine with melted coconut oil.}
In the bowl of a stand mixer or in a large bowl with a hand mixer, beat together butter, honey and vanilla extract until smooth.
Stop the mixer and add in the flour, baking soda, salt, cinnamon and oats. Beat until everything is well-combined, but try not to over-mix.
Spread the mixture into the prepared cake pan and smooth the top as evenly as possible. Bake for 15-17 minutes or until the top is golden brown and a toothpick inserted in the center comes out clean. Remove from oven and allow to cool.
Make Blackberry Jam: Meanwhile, combine the blackberries, water and honey in a small saucepan over medium heat. Bring to a boil, then reduce heat to medium and allow the mixture to simmer until the berries have softened, stirring often. Using a potato masher or a fork, mash the berries to allow them to release their juices. Simmer for another 2 minutes or so, then add in the chia seeds and stir for about another minute. Add the lemon juice and vanilla extract, and cook for another 30 seconds to 1 minute or until the mixture has thickened a bit. {When you run a spatula along the bottom it should leave a trail for a second. The mixture will continue to thicken as it cools, so don't worry if it still seems a little runny.} Remove from heat and allow to cool and thicken.
Scoop the Greek yogurt for the web drizzle into a small piping bag or a zip top bag with one corner snipped. Set aside.
Assemble Pizza: Spread the blackberry jam evenly over the cookie base. Pipe the spider web using the yogurt. {I start by piping a large cross, then an "X" creating 8 spokes that meet in the center, then I pipe curved lines inside each "slice" to create the web.
Finally, using your sliced blackberries, create the "spiders" scattered on the web. Gently push 2 nonpareils into the head portion of the spiders to create eyes. Gently poke toothpicks or licorice into the blackberry to create legs. Serve immediately.