Preheat the oven to 350F. Line a 9x13-inch baking dish with parchment paper.
In a large bowl, add the yogurt, almond butter, eggs, molasses, maple syrup, and vanilla. Whisk until smooth and combined.
Add the oats, spices, salt and baking soda and use a rubber spatula to mix until combined. Mix in the blueberries until evenly distributed.
Transfer to the baking dish and use a rubber spatula to spread into an even layer. Top with walnuts (if using). Bake for 35 minutes or until browned on top and a knife inserted into the center comes out clean.
Let it cool off for at least 15 minutes, but ideally 30-60 or overnight. The longer you let it cool down, the better it will slice. Grab the parchment to remove the bars from the baking dish and place on a cutting board. Slice into 9-12 bars. It will be a bit crumbly.
These are delicious warm and room temp, but I also love them cold out of the fridge. You can eat them plain, topped with Greek yogurt, or with a couple pats of butter for a more decadent treat.