Air Carrier Captain reported encountering severe turbulence in cruise after entering a cloud resulting in loss of control and altitude and airspeed variations. After the turbulence encounter the flight continued to its destination without any further issues.

Narrative

When in cruise flight at FL350; we were over ZALEA on the MRRSH3 SID out of Dallas; when we saw the top of the weather exceeded our altitude. We were assigned 35;000 feet and our weight restriction did not allow us to climb any higher. I was Pilot Monitoring at the time and there were no reports of any severe turbulence; just some reports of light to moderate chop so we told the flight attendants on the preflight briefing to remain seated until we were clear of the chop. As we approached the cloud; I asked ATC about it; which they reported back that there was heavy precipitation 3-4 miles off our course and we would be clear of it. Before entering the cloud; we slowed to our turbulent penetration airspeed of 270. Once inside the cloud; we experienced severe turbulence with altitude variations of +/-400 feet and our airspeed changing +/-25 KTS as well. The Pilot Flying did a great job of trying to control the speed and the auto throttles eventually kicked off. We were in the turbulence for about a minute and afterwards I called the Flight Attendants to make sure no one was harmed and we advised ATC. I messaged Dispatch to let him know of the ride conditions for other flights. The flight continued without any further issues. I called maintenance when we landed and they told me that no Aircraft Maintenance List entry was required.There was a big line of weather extending up most of the US. When we flew into Dallas earlier; we experienced a mostly light/moderate ride but no severe. The weather must have built up more in the time between our two flights and from what ATC said; we were the first ones to experience the severe.Even though the line of weather was extremely long; try to find a better spot to go through it. We weren't painting anything on our radar but the cloud we entered looked a little taller than the surrounding clouds.