Preheat the oven to 350 degrees.
Fill a large pot of water and salt generously. Heat over medium high heat and bring to a boil.
While the water heats, prepare the ground lamb mixture. In a mixing bowl, combine the ground lamb, garlic, parsley, paprika, salt and cinnamon. Use your hands to really massage it together until fully combined. Set aside.
Heat a large skillet on medium heat. Season the pan with oil and once it’s shimmering, add the onion to the pan. Sauté the onion for 2-3 minutes until lightly golden brown. If the pan seems to get a little dry, add another splash before the next step.
Add the lamb mixture to the skillet and use a large wooden spoon or spatula to break up the pieces and combine it with the onion. Let this cool for 4-5 minutes, until all of the lamb is no longer pink and the texture firms up.
Add the 1/2 cup Greek yogurt and 1/4 cup tomato paste to the pan and mix with your spoon/spatula until combined, 1-2 minutes. Remove the meat mixture from the heat and set aside.
Add the shells to the pot of boiling water and cook until al dente. This should be listed on the packaging under “pre-baking” cook time. My shells took 9 minutes.
As the shells cook, periodically stir with a spoon to make sure they don’t stick together.
In a mixing bowl, combine 1 cup of Greek yogurt, 1/4 tsp salt and 2 tsp of minced garlic.
In another bowl, combine the 6 tbsp tomato paste and 1/4 cup of olive oil. Sprinkle 1/8 tsp of salt and mix together until combined.
Drain the shells from the water and wait a few minutes for them to cool, but make sure they don’t stick together!
Take a clean baking dish (the one that you’re going to bake the shells in) and scoop some of the yogurt mixture and tomato paste mixture onto the bottom of the dish. Spread the mixture out with the back of your spoon to create a flavorful foundation for your shells.
With clean hands, fill each shell generously with some of the meat mixture. Once filled, place the shell in the baking dish. Repeat with all the shells and create a lineup in the baking dish.
Dollop the remaining tomato paste and yogurt sauce into the spaces surrounding the stuffed shells and generously drizzle olive oil on top. It may look ugly but it will come together.
Cover with foil and bake for 10-15 minutes at 350 degrees.
Remove from the heat and top generously with minced parsley and olive oil. Serve immediately! Enjoy!