Cascading an Op Amp at a desired frequency question
What I'm confused about is designing around the desired -3dB frequency


I think the question is trying to test you on your understanding of the open-loop gain for an op-amp and how the 3dB point changes as you lower the gain with feedback resistors. For instance: -



In the example above, the feedback and input resistors are chosen so that the "closed-loop" gain at DC is 20 dB (a real number gain value of 10). At this level of amplification you can see that the op-amp will run-out-of-steam at a frequency about 50 kHz. This is the approximate 3 dB point (half power point). If we chose a closed loop gain of 55 dB (G = 560), the 3 dB point would be much lower at 1 kHz.

As an aside, this introduces the concept of the op-amp having a numerically fixed (well, fairly fixed) value of gain x bandwidth often called the GBWP or gain-bandwidth-product. G = 10 and BW = 50 kHz is pretty close to G = 560 and a BW of 1 kHz. I'm sure with a better picture of the open-loop gain it would be numerically quite close in both scenarios.

So, with two cascaded op-amps, the best (highest) 3 dB point you can get is when both have the same gain because, if one had a much smaller gain than the other, the device operating at the higher gain would dictate the 3 dB point and this will inevitably be lower than if both gains (and both op-amps) are the same.