Begin by setting a large 6 to 8 quart pot out and filling it one-third full of water. Peel the russet potatoes, then chop them into 1 to 2 inch chunks. It’s best if they are close in size for even cooking. As you chop the potatoes, add them to the pot. Once all the potatoes are in the pot, make sure the water is at least 2 inches above the top of the potatoes. If not, add additional water.
Place the pot on the stovetop and turn the heat to high. Add a couple large pinches of salt to the water. Bring the potatoes to a boil and set a timer for 20 minutes. When the timer goes off, check the potatoes with a fork. You should be able to easily mash the potato with the fork. If not, cook for another 5 minutes or so until tender.
Meanwhile, prepare the gravy. Set a smaller pot over medium heat. Place butter and flour in the pot. Use a whisk to mix the butter and flour as the butter melts. Continue to whisk until you achieve a fluffy golden roux, about 2 to 3 minutes.
Add the beef base, chicken base, and garlic powder. Mix until the ingredients are well incorporated into the roux. Gradually add in 2 cups of water, pouring and whisking a little at a time to avoid lumps. Allow the gravy to simmer and thicken for 2 to 3 minutes, then turn off the heat. Remember, the gravy will continue to thicken as it cools.
Once the potatoes are tender, set out a colander. Pour the water and potatoes into the colander and allow them to drain for at least 5 minutes. This step is crucial; dry potatoes mash better, creating a light and fluffy texture.
Return the empty hot cooking pot to the stove and place butter inside, followed by the half-and-half. Allow the butter to melt and the half-and-half to warm up while the potatoes are drying.
Once the potatoes have dried, place some of the potato chunks in a ricer. Press the potatoes through the ricer into the melted butter mixture. Continue this process until all the potatoes are riced, stirring the riced potatoes with the butter and half-and-half until very smooth and fluffy. Taste, adding salt and pepper as needed.
If you prefer, you can also return the dried potatoes to the pot and use a potato masher to mash them until smooth.
Finally, re-warm the gravy if necessary. Move the mashed potatoes to a serving bowl and generously pour the warm gravy over the top. Serve immediately and enjoy!