Preheat the oven to 375F/190C.

Place condensed milk in a bowl, then whisk in the egg yolks and lemon juice and zest. Pour into the tart pan on top of the crust.

To make the meringue--make sure your bowl is free of any grease--don't use a plastic bowl. Glass or stainless is best. I usually re-wash the bowl and rinse it well then swish some white vinegar around in the bowl then rinse again and dry with a clean paper towel.

If using a stand mixer, use the whisk attachment.

Place the egg whites in the bowl and beat at very high speed until the whites look like clouds, then slowly add the sugar about a tablespoon at a time, until the whites form stiff peaks.

Place the meringue in dollops on top of the filling--this makes it easier to spread (trust me on this). Using the back of a spoon, gently cover the filling and up and over the crust top. Use the spoon to make gentle swirls

Bake for 15-20 minutes or until meringue starts to get golden on the swirls.

Let stand for about 30 minutes, then serve when warm