For the arancini: Heat a Dutch oven over medium-high heat. Add the olive oil, butter and shallot and cook until the shallot is soft and fragrant, about 2 minutes. Add the rice and toast, stirring often to coat the rice in the flavored oil, for 2 more minutes. Season with the salt. Deglaze with the white wine and cook, stirring often, until almost entirely absorbed. Add a cup of the broth and cook, stirring constantly, until the liquid is nearly absorbed. Continue to cook until the rice is just tender and the mixture is creamy, adding more broth by the cup and stirring often, about 35 minutes total.
Stir in the Parmesan cheese. Pour one-third of the risotto into a separate bowl and one-third into another bowl so you have 3 separate bases. To the risotto in one of the bowls, stir in the pesto. To the risotto in the pot, stir in the marinara. Refrigerate until completely cool.
For the breading and serving: In a Dutch oven, heat 4 inches of oil to 350 degrees F on a deep-fry thermometer.
Set up a breading station by placing the flour in one bowl, the eggs in another bowl and the breadcrumbs in a third bowl. Using a 1-ounce scoop, form the risotto into 1 1/2-inch balls. Roll them in the flour first, followed by the eggs and finishing with the breadcrumbs. Fry the arancini until golden brown and warmed through, about 3 minutes. Serve with marinara on the side for dipping, if desired.