Heat olive oil in a medium saute pan. Add quartered fennel bulbs and brown on all sides, rotating every 3-4 minutes.

Add in 1/2 cup vegetable stock, orange juice, and 1/8 tsp salt. Turn the heat up to high to bring to a boil. Once boiling, turn the heat down to lower, cover, and simmer for 15 to 20 minutes, or until the fennel is tender.

Meanwhile, warm the remaining vegetable stock over medium in a small saucepan.

In a large sauce or saute pan, warm 1 Tbsp butter and 1 Tbsp olive oil over medium. Add shallot, garlic cloves, and celery and saute until softened, 5 to 8 minutes. Add 1/8 tsp salt.

Turn the heat up to medium-high and add the rice. Toast the rice by stirring it around constantly until slightly translucent, about 1 minute. Add the white wine and, stirring often, cook until it is almost absorbed.

Add about 1/2 cup of vegetable stock and stir until most of that has been absorbed. You want the stock to be at a simmer but not a boil so turn the heat down to medium at this point if it's past a simmer. Repeat with more 1/2 cup ladles full of the warm broth, waiting until they are mostly absorbed between each ladle, and stirring often. This whole process should take about 15 minutes.

To check if the risotto is done, it should have a bite to it but be mostly cooked through (it will also continue to cook slightly afterwards so you'll want to keep that in mind when tasting).

Once all the broth has been used and it's al dante, reomve from heat and stir in the remaining butter, braised fennel bulbs (along with any lingering juices in the pan), Parmesan, mascarpone, orange zest, and some fresh black pepper. Taste and add more salt or pepper, if needed.

Divide into bowls and garnish with fennel fronds. Serve right away.