Bring a 3-qt pot of water to a boil and add two good pinches of salt and the Arborio rice. Cook, stirring occasionally for about 20 minutes or until the rice is tender. Drain the rice in a colander and run cold water until the rice is cool. Drain well.
Meanwhile in a medium bowl, whisk together the yogurt, eggs, chives, Fontina cheese, 1-1/4 teaspoon salt, and pepper. Add the cooled rice and mix to combine. Cover with plastic wrap and refrigerate for at least 2 hours or overnight.
When you are ready to cook the cakes, preheat the oven to 250 degrees F. Line a baking sheet with parchment paper.
Put the panko crumbs in a shallow bowl. Make the cakes using a 2-1/4 inch ice-cream scoop or a large spoon. Form each ball into a patty 3-inches in diameter and about 3/4 inch thick. Coat each patty with the panko crumbs on both sides.
In a large skillet over medium-high heat add 3 tablespoons of olive oil. Add the patties to the skillet with hot oil and cook for about 3 minutes per side, or until crispy and brown. Transfer the cooked patties to the baking sheet and hold them in the warm oven for up to 30 minutes. Continue to cook the remaining patties, add more olive oil if needed. Serve hot.