Oxtoby made four changes to the side narrowly beaten by Portugal at Mourneview Park last month in what was arguably the finest performance of her reign to date.
In-form forwards Casey Howe and Beattie were among those who started, in place of the experienced Lauren Wade and Simone Magill.
Northern Ireland looked to get off to a fast start as they did in the Portugal game, but it was Malta who began on the front foot in the searing heat in Ta’ Qali.
They had an early chance to take the lead after just two minutes as Rachel Dugdale surrendered possession in a dangerous area. Maria Farrugi took advantage, striding forward before finding Haley Bugeja, whose low effort rebounded off the far post.
Kailey Willis then had a shot easily stopped by Jackie Burns, who was called into action again soon after to tip a towering header from the forward over the crossbar.
The breakthrough came against the run of play on nine minutes with Lipman attempting a routine back-pass to goalkeeper Patricia Ebejer. The defender misjudged the weight on the pass and it flew past Ebejer and nestled in the bottom corner.
