When the dough has almost doubled in size, grease a very sharp knife (bakers use a special safety razor blade) and slash the top 3 to 4 times. Allow to rise for a further 5-10 minutes then bake. Don’t be scared to cut deeply into the dough as this will form a great cross when baked. This will allow the bread to expand quickly and avoids “blow outs” when bubbles form under the crust. If you are baking rolls you can use scissor to snip the top.