Here is the book description from Amazon.
As William the Conqueror’s men attempt to stamp out the flames of rebellion, a prophecy is uttered. A bedraggled woman in a ruined chapel speaks of civilizations in conflict, armed by the engines of God…
And that prophecy proves to be true as the fearsome war between Christianity and Islam [...]
Other Time Lines is a website has a lot of interesting alternative histories and Islam features in many of these alternative timelines. Here are some examples.
Timeline 218 A time line where the Russians covert to Islam and the Ottomans earlier than in OTL.
Timeline 803 What if the Turks had won the battle of Lepanto and [...]
In Islands in the Sea (published in Departures) by Harry Turtledove, the Muslim invasion of Constantinople succeeds in 715 and southern Europe is conquered by Muslims 700 earlier than in OTL. In the story the Muslims and Christians are trying to convince the king of Bulgars to convert to their respective religions. In the end [...]
In A Study of History Toynbee ponders upon a few alternative history scenarios that are relatrd to Islam in one way or another.
The Forfeited Birthright of the Abortive Far Eastern Christian Civilization: In this scenario the Ummayids do not reinvade Central Asia after their defeat at Kish-Samarkand pass in 731. The Central Asians adapt Nestorian [...]
The story is set in an alternative world where the Black Death plague killed almost all of the inhabitants of Western Europe, instead of one-third in 0TL. The story is set in 2042 where the world is dominated by Muslims. The Chinese and the Aztecs are featured as well. Coincidently the capital of the Saracen [...]
This is one of the best novels on alternative history involving Islam. In this alternative history the bubonic plague kills 99% of the population in Europe, leaving the Islamic world and China as contest over the control of the world with India caught in the Middle. The main characters are reincarnated many times and the [...]
Here is a synopsis from Fictionwise.
The ambitious Sultan of Alpha Centauri can only claim the illustrious title of Caliph if he makes a ritual pilgrimage to the holy city of Mecca. This journey completed, he will rule the entire population of the greater Islamic universe. But human knowledge has not yet been able to overcome [...]
The history of Islam in the 20th century in this story is different from OTL. Here is a description from Fictionwise.
For a thousand years the Great Awakening has spread the teachings of Islam to all of the far corners of the known universe. Without a Caliph at its head, the great Muslim empire had been [...]
GURPS is a well known book and is actually a collection of short alternative history stories.
Caliph by Hite, Kenneth, Craig Neumeier, and Michael Schiffer
Published in GURPS Alternate Earths II
In OTL the knowledge of paper making arrived in the Islamic world in 749 after the historic battle of Talas river when some Chinese were captured who [...]
In If the Moors in Spain had Won (1931) Philip Guedalla speculates a world where the Muslim Granada had not fallen in 1491. Ferdinand’s army is defeated at Lanjaron in 1491. The alternate history is the long and enlightened history of the kingdom of Granada from 1491 to the Paris Peace Conference of 1919.
