Biscuit Troubleshooting: What Went Wrong?
From Old Fashioned Tips

I've never had that problem, but when I was first learning to make scratch biscuits mine were hard as rocks. They should be made with cold butter, shortening or margarine- -very cold--don't let it sit out. The dough should be handled gently and only as much as necessary to mix. The dough shouldn't be smooth--if it's overworked the biscuits will be hard like mine used to be. These two things are the most important. If you are already doing that, then try placing the biscuits closer together on the baking sheet--less than an inch apart. If they are soft and fluffy with a good taste then don't worry about it! Some people like their biscuits crusty on top, so it depends on what you prefer. One other thought--try brushing a mixture of water and egg white on the top of the biscuits before baking.

READER'S ADVICE
I bake biscuits in a 13x9 cake pan placing about 4 biscuits in each row. The biscuits push against each other and the sides of the pan making them wonderfully fluffy. I also put a dab of butter on top of each biscuit before baking which adds to the flavor and texture. It might also prevent the top from splitting. -B. Painter

When I was first learning to bake biscuits, my mother (who never baked her own biscuits) said she remembered that her mother had once said that the biscuits should be close enough together to lightly touch in the pan. (I don't think she knew why, but your comment that I quoted reminded me of it.) I don't know if that's the secret, but I've always baked mine like that and never had a split. ~Sharon

Cracks on top of the biscuits could be due to an oven that is too hot or uneven heating. Just a thought... ~Sue

We who are members at the www.cakemixdoctor.com forum learned long ago, if you will turn the heat down, it produces a more level and flat topped cake. Reduce the heat down, from 350° to 325 and see the difference. :-) Just wanted to share a tip that has made all the difference in the way many of our cakes bake. ~Mary B.

I believe it could be too much flour used to knead the dough. Too much flour also makes dough tough. I use 2 cups self-rising flour, 3 tablespoons shortening, worked into the flour with fingers, then stir in enough milk to make a very loose dough. Spoon onto floured board and knead just enough to pat the dough out to desired thickness. Cut and place on well greased pan (I use iron skillet) and dot top of each biscuit with butter. My grandma always brushed tops with milk, this works well too. Bake in preheated 500 degree oven. (I have found that White Lily flour makes the best ever!) ~Nancy

I agree you shouldn't handle the dough overly much...my grandmother put her biscuit pan in the oven and heated up the oil (a little); spread a tad on 1/2 of dough, folded the other half of the dough over the oiled half, cut her biscuits and then placed them in the pan, flipped them over once and then into the oven. The small amount of oil in the center makes them open right in half. ~seer