Heat 1 tablespoon of butter and olive oil in a large, heavy-bottomed saucepan over medium-high heat. Add the onion; cook and stir until it begins to turn golden brown at the edges, about 2 minutes. Pour in the rice, and stir until the rice is coated in oil and has started to toast, 2 to 3 minutes. Reduce the heat to medium and stir in the white wine. Let it cook until it has mostly evaporated, then stir in one-third of the boiling vegetable broth; continue stirring until incorporated. Repeat this process twice more, stirring constantly. Incorporating the broth should take 15 to 20 minutes in all.

When the rice is mostly tender, but still has a very slight crunch, stir in the hearts of palm and Parmesan cheese; season with salt and pepper. Cook for another minute to heat through then stir in parsley and butter, and serve immediately.