I am working on a multivariate Gaussian distribution with mean $\mu \in \mathbb{R}^d$ and the variance-covariance $\Sigma \in S^{d\times d}$ where $S$ denotes the set of symmetric matrices.
When I am trying to maximize the log-likelihood of some observations (with respect to $\Sigma)$, I am basically trying to take the first-order conditions, and I need to derive the following:
$$\nabla_{\Sigma} \left( \mu^\top \Sigma^{-1}\mu \right)$$
This derivative is too complicated for me since $\Sigma$ is a matrix.
How can I solve these?