In a medium bowl, toss the shrimp with 1 tablespoon olive oil and 2 tablespoons McCormick® Zesty Spice Blend until well coated.
Heat a 9-inch cast iron skillet over medium-high heat. Working in batches of 5–6, cook the shrimp for 45 seconds on each side, until starting to turn golden and opaque. Transfer to a clean medium bowl and repeat with the remaining shrimp.
Add the remaining tablespoon olive oil, remaining tablespoon McCormick® Zesty Spice Blend, and the tomatoes to the bowl with the shrimp and toss to combine.
Remove the skillet from the heat and wipe out any crispy bits. Let the skillet cool for about 10 minutes.
Return the skillet to medium heat and add the chicken broth and cream, whisking to combine. Cook until the liquid begins to steam, about 5 minutes.
Slowly pour in the polenta, whisking well to prevent clumps from forming. Cook for 12–15 minutes, until the polenta is thick and the grains are tender, whisking constantly to prevent the polenta at the bottom of the pan from burning or clumping. Remove the pan from the heat.
Whisk in the Parmesan cheese and butter, then fold in the spinach. It will wilt from the residual heat.
Set an oven rack 3 inches from the broiler and turn the broiler on high.
Arrange the shrimp on top of the polenta in the pan and top with the tomatoes and any remaining marinade from the bowl.
Broil the skillet for 3 minutes, checking occasionally to avoid burning, until the polenta is golden brown and the tomatoes soften.