Halve and peel onion. Slice halves into thin strips. Place a medium non-stick pan over medium-high heat. Add 2 tsp. olive oil, onions, and a pinch of salt and pepper to hot pan and stir occasionally until softened, 5 minutes. Add 3/4 cup water and cranberry sauce and stir occasionally until mix is a jam-like consistency, 8-12 minutes. Transfer onions to a plate. Wipe pan clean and reserve. While onions caramelize, prepare ingredients.

Trim stems off Brussels sprouts and thinly slice. Halve grape tomatoes. Coarsely chop smoked almonds.

In a mixing bowl, thoroughly combine Brussels sprouts, tomato, half the almonds (reserve remaining for garnish), 2 tsp. olive oil, 1/4 tsp. salt, and a pinch of pepper.

Remove puff pastry from refrigerator and remove paper from between sheets. Place pastry on prepared baking sheet. Fold each side 1/2" over on top of square. Using two fingers, pinch sides to make a decorative edge.

Divide mozzarella cheese equally between four puff pastry squares, then divide caramelized onions equally. Place a mound of Brussels-tomato mixture on each tart. Don't worry if mixture spills over the edge. Bake until pastry is golden brown and filling is beginning to char, 20-25 minutes, rotating baking sheet after 10 minutes. Garnish with remaining almonds and blue cheese and enjoy!