A method of making a dome plate for a gas turbine engine combustor includes forming an annular body and forming a plurality of swirler openings in the annular body. Then, an array of impingement cooling holes and an array of blow-off holes are electrically discharge machined into the annular body adjacent to each swirler opening. For each one of the plurality of swirler openings, the corresponding array of impingement cooling holes and the corresponding array of blow-off holes are machined in a single electrical discharge machining operation. This results in an annular dome plate having radially outer and inner curved corners that define a single radius of curvature. The blow-off holes are located in at least one of the outer and inner curved corners.