Heat 1 teaspoon oil in a heavy, 12-inch, sauté pan (or high-sided cast iron skillet). Add chicken and brown over medium-high heat until golden on all sides, 1-2 min. Remove and set aside.
Add the remaining oil to the pan and heat over medium-high heat. Add the garlic and onions and saute 1-2 min. Add the tomatoes (un-drained), paprika, rosemary, salt, and pepper. Sauté until the mixture begins to caramelize and darken, 3-4 min.
Mix in the dry rice and stock.
Mix in uncooked shrimp and chicken.
Bring the mixture to a simmer and reduce heat to medium-low. Let the paella cook, uncovered and undisturbed, for 20-25 min, until it looks like all the liquid has been absorbed.
Then, crank the heat to high for 1 min until you can smell the rice toasting.
Serve immediately.
Notes
* Feel free to substitute ⅛ teaspoon saffron if you have it!