Heat the olive oil and butter over medium-high heat in a large skillet.
Add shallots to the skillet and stir to coat, then cook 5-6 minutes until softened.
Stir the uncooked rice into the shallots. Let rice cook about 4 minutes, until fragrant, then stir in the white wine, deglazing the bottom of the skillet as you go. Cook a few minutes, stirring regularly, until the wine is almost totally absorbed.
Reduce heat under the skillet to medium. Ladle in ½- ¾ cup of the simmering chicken broth into the skillet. Stir and let cook rice, stirring regularly, until liquid is almost totally absorbed. Repeat the "add-broth-stir-until-liquid-absorbed" process, adding more broth whenever the pan starts to get dry. Be patient – this will take 40-45 minutes.** SEE BELOW FOR RISOTTO COOKING TIPS.
Once the risotto is cooked through, stir the lemon juice into the skillet and let cook until absorbed.
Turn off the heat under the skillet and the pot that held the chicken broth. Stir the grated cheese, lemon zest, mascarpone cheese, salt, and pepper into the risotto. Taste and adjust seasoning as desired.
Tear the fresh basil into small pieces and stir into the hot risotto.
Serve Cream Lemon Risotto immediately, garnishing with more grated cheese and fresh basil if desired.