Hi Giovanni,
Here are three options for settling the espresso.
Glass A: single-walled gives good settling.
Glass B: Double walled gives a lesser settlement because of the shape of the glass.
Tank C: Gives the most settlement, watch this from beginning to end, a nice layer of foam will form and a dark bottom.
1: Glas A Settling
2: Glas B Double-walled
3: Tank C