Heat a heavy skillet over medium heat. Add oil and wait until it shimmers. Add garlic and cook quickly, being careful not to burn, about 1 minute. Carefully transfer garlic slices to a paper towel-lined plate. Set aside.
Add tomatoes, red pepper flakes, and salt to the same skillet. Stir and crush down tomatoes with a wooden spoon. Cover and cook for 5 minutes.
Meanwhile, bring a large pot of salted water to a boil and cook pasta until tender yet firm to the bite, about 8 minutes. Drain and set aside.
Remove lid from sauce and stir. Add in tuna steaks. Cover and cook until tuna flakes easily with a fork, 8 to 10 minutes. Add 1/2 of the fried garlic, parsley, cream, and 1/2 of the basil.
To serve, add pasta to bowls and ladle tuna sauce on top. Garnish with remaining basil chiffonade and fried garlic. Serve immediately.