To solve the equation
\[ -(x - 3)^2 - 3 = 7, \]
we first isolate the squared term. We can add 3 to both sides:
\[ -(x - 3)^2 = 7 + 3, \] \[ -(x - 3)^2 = 10. \]
Next, we can multiply both sides by -1:
\[ (x - 3)^2 = -10. \]
Now, we take the square root of both sides. Remember that taking the square root of a negative number involves using imaginary numbers:
\[ x - 3 = \pm \sqrt{-10}. \]
We can express \(\sqrt{-10}\) using imaginary numbers:
\[ \sqrt{-10} = \sqrt{10}i. \]
Thus, we have:
\[ x - 3 = \pm \sqrt{10} i. \]
To solve for \(x\), we add 3 to both sides:
\[ x = 3 \pm \sqrt{10}i. \]
Now we can express the solutions in standard complex number form \(a \pm bi\):
\[ x = 3 + \sqrt{10}i \quad \text{and} \quad x = 3 - \sqrt{10}i. \]
Thus, the solutions are
\[ \boxed{3 \pm \sqrt{10}i}. \]