Averaging and plot multiple mean_spectrums

Dear MNE users,

I calculated the power spectrum for multiple conditions, across multiple subjects, using the following code.

spectrum = epochs_cleaned.compute_psd(fmin=2, fmax=40., n_fft = 500, n_overlap = int(0.50 * 500), method = 'welch',  n_jobs=-1)
# average across epochs first
mean_spectrum = spectrum.average()

I would like now to average the mean_spectrums calculated as below, across participants, and then plot each averaged condition as I was doing at the single subject / single condition level using

mean_spectrum.plot_topomap(cmap = 'RdBu_r')

How can I achieve this? As in, how can I aggregate different mean_spectrums and visualise the results?

Best,
Davide