In a medium size saucepan, bring 3 cups of water to a boil with a pinch of salt. Slowly stir in the polenta. Reduce the heat to low and simmer gently for 30 minutes, stirring often to prevent the polenta from sticking.
Strain the cashews. Heat a pan over low heat and add the olive oil, followed by the garlic. Cook until the garlic begins to soften, stirring often. Cool to room temperature.
Place the cashews in a blender with the garlic and its cooking oil, lemon juice, salt, white beans and water and blend until smooth. With the blender still going, slowly pour in the remaining 2 tablespoons oil.
When the polenta is almost done, cook the greens. Heat a sauté pan and add the olive oil, then the greens. Cook over medium heat for 5 minutes, stirring often, until tender. Season with salt.
Take the polenta off the heat and stir in the cream sauce. Season, to taste. Serve topped with greens and a few grinds of fresh pepper.