By allowing the European Central Bank to monetize the debt of each and every member country, and ridding the so-called growth & stability pact. or getting rid of the Euro altogether, which is preferable.
My simple observation is that regional monetary policy need also a regional fiscal policy. Fiscal and monetary policy needs to work together. In addition, EU needs a better mechanisms to control all members national budgets that can facilitate the taxation structure and government spending respectively.
Coordinated fiscal policies appear to be even more necessary the more the common monetary policy fails to overcome the period of low growth or stagnation in many countries. If you renember the financial crisis years, national fiscal policies were largely uncoordinated. Since then, we introduced the European Semester and so on but these measures are biased towards fiscal consolidation. As an expansive element, public investments should be excluded from the calculation of budget deficits. Besides that, the deficit countries in the euro area should continue to implement structural reforms in order to improve competitiveness. But at the same time, the consolidation targets could be less ambitious.