One example off the top of my head is the Battle (or Skirmish) of Garcia Hernandez, 23rd July 1812 where a King's German Legion cavalry brigade, part of a force pursuing French forces after the Allied victory at Salamanca which had been fought the day before, managed this feat when the small 4th cavalry brigade, comprised of the 1st and 2nd KGL Dragoons, managed to break, in rapid succession and at the charge, two (perhaps three) infantry squares from General Foy's division, which itself was acting as the French army's rearguard.

Usually cavalry would not perform such an attack (attacking infantry in square) but the Allies at first thought there were only French cavalry and horse artillery in the area when the attack order was given. The advancing German cavalry (possibly by then already charging) only becoming aware of the French infantry squares at such close quarters when they passed some obscuring terrain.

The unique nature of the event itself was caused, according to reports and eyewitnesses, because the initial French infantry square held their fire too long against elements of the brigade who had charged them after taking fire from the square. When the French infantry finally fired their next volley, the resulting damage caused a dying horse to crash into the ranks of French infantry, causing a gap for following cavalrymen to exploit. "...At this critical moment, when the sword was about to be matched against the firelock, and the chivalrous horsemen against the firm foot soldier ... [came the volley or an accidental shot] which killing a horse, caused it and the rider to fall upon the bayonets ... For a path was now opened, and the impatient troopers rushing in amid the blazing fire, while men and horses fell fast before the muskets of the French infantry, their firm formation was destroyed, and the whole battalion were either cut down or taken prisoner."

The sight of the collapse of the first square is thought to have caused a shock and morale loss amongst the second infantry square, who recoiled in the face of the charging cavalry "... the moral force of the French infantry [in the second square] had been shaken by the fearful overthrow which they had just witnessed, and some timid individuals leaving their ranks, [the cavalry] rushed in ... the square broke, and the greater part of the battalion was cut down or captured". However, this disorder amongst the second square referred to in the quote, could actually be referring to formed survivors of the first square retreating uphill who were then overwhelmed.

Another square which was charged and broken (possibly a third, but more likely a second actual square - the "second" square being the aforementioned formed survivors of the first) may have been attempting to withdraw uphill (not easy in that formation) and that this also contributed to confusion and amongst the infantry. Certainly a final charge by the dragoons soon after against a fully formed and prepared French infantry square from a different regiment was seen off by the defending French with heavy casualties amongst the Allied cavalry.

The debate over whether it was two or three squares is, as mentioned above, due to the confused and conflicting nature of some of the eyewitness accounts. The argument it was three is attributed to the cavalry charging that withdrawing formed unit of French infantrymen who may or who may not have been in square, before moving onto the second (or third depending on your view) square. The consensus amongst historians seems to be that certainly at least two full regiment-sized squares were broken in this action.

The quotations are from North Ludlow Beamish's History of the King's German Legion, II, (1837), however you might find a more detailed (and more dispassionate) account in published works such as:

John Keegan gives a summary of the event in his excellent The Face of Battle (Vintage, 1977)

I would also recommend Peter Edwards, Salamanca 1812: Wellington's Year of Victories (The Praetorian Press, 2013)