For the mushrooms:

1. Heat butter and oil in a large heavy-bottomed saute pan or dutch oven over medium-high heat until the butter is melted and hot. Add 1/3 - 1/2 of the mushrooms in an even layer. It's essential for even browning that the mushrooms are not crowded, so use your best judgment on batch size based on the size of your pan. Cook undisturbed on one side, about 3-5 minutes until they begin to brown, then sprinkle with a pinch of the thyme and stir. As the mushrooms cook, they will disgorge liquid and begin to look glossy. Cook an additional 3-5 minutes until all liquid has left the pan and they are nice and golden, then add salt and pepper at the end and reserve to the side. Repeat with the remaining mushrooms until all batches are cooked and reserved to the side.

For the shallots:

I always cook these separately and reserve them to the side to serve on top for others as I do not tolerate onions very well myself. If this isn't an issue for you, you can cook them into the risotto directly before adding the Arborio rice to cook.

1. In a medium skillet, over medium heat melt the butter. Add the shallots and allow to cook, stirring occasionally until browned as desired, then reserve to the side.

For the risotto:

1. In a medium saucepan, heat the chicken broth/stock over medium-high heat until it begins to simmer, then turn the heat to low to maintain it's warmth.
2. Continuing with the same pan you cooked the mushrooms in, lower the heat to medium and add the wine and lemon juice to deglaze the pan, scraping up any browned bits that may be lingering from the mushrooms. Allow the liquid to simmer and reduce by half, then add the Arborio rice and stir for 1-2 minutes, or until the rice begins to look translucent.
3. Add about 8 oz (1 cup) of the hot chicken broth/stock (You can eyeball this with a large ladle). Stir often (but not constantly) until the liquid is mostly absorbed. Repeat ladling 8 oz (1 cup) of hot broth and stirring often until absorbed 2 more times, then add the frozen peas, stirring to combine. Repeat ladling 8 oz (1 cup) of hot broth and stirring often until absorbed a final 2 times. You will have added 8 oz ( 1 cup) of broth a total of 5 times. This step takes about 15-20 minutes but is essential to a superbly textured risotto.
4. Once the final measure of broth has been mostly absorbed, add the heavy cream and stir to combine until warmed through. Then add the parmesan and stir to combine. Taste for salt and pepper and add as desired. I generally find that my chicken broth/stock and the combined parmesan have added the right amount of salt to the dish, but you may wish to finish with a measure of Kosher salt if your broth is on the less salty side.
5. I prefer to stir in half of the mushrooms and reserve the other half for topping the risotto once it has been dished into bowls. Finish each bowl with an optional measure of fresh chopped chives and the reserved shallots.